Bundles of fibers useful for moving liquids at high fluxes and acquisition/distribution structures that use the bundles

ABSTRACT

The ability to transport body liquids in consumer products such as diapers, incontinents and feminine napkins is a key factor in their performance. This invention is designed to provide specific high fluxes (volume of liquid/(time*mass of polymer) of aqueous liquids in designated directions using bundles of new specially designed fibers. The key factors for the bundles are a high specific adhesion for the liquid of interest, a high specific volume of the bundle itself, and alignment of the fibers within the bundle. The invention includes novel liquid acquisition/distribution systems and absorbent products that include a liquid acquisition/distribution system which may incorporate the novel bundles of fibers.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a divisional application of application Ser. No. 08/912,608,filed Aug. 15, 1997, issued as U.S. Pat. No. 6,103,376, which claimsbenefit of Provisional Application Serial No. 60/024,301 filed Aug. 22,1996.

TECHNICAL FIELD

This invention relates to structures that transport liquids by capillaryaction. More particularly, this invention relates to fibers and personalhygiene absorbent products such as diapers, adult incontinent pads, andfeminine napkins, and to the flow, distribution, and acquisition ofliquids in the fibers and products.

BACKGROUND OF THE INVENTION

In the past several years there has been great interest in polymerstructures that provide liquid transport and storage.

U.S. Pat. No. 5,200,248 to Thompson et al. issued Apr. 6, 1993 anddiscloses capillary channel structures such as fibers that includeintrastructure capillary channels that store and transport liquid. TheThompson et al. patent disclosed that these capillary channel fibers maybe coated with materials that provide an adhesion tension with water ofat least 25 dynes/cm. The teachings and especially the definitions inthe Thompson et al. patent are hereby incorporated by reference as iffully set forth herein. This specification provides values for fibersshown in examples herein for some of the quantities defined in theThompson et al. patent.

European patent application No. EP 0 516 730 B1 claims priority from theapplication that matured into the Thompson et al. patent.

U.S. Pat. No 5,611,981 to Phillips et al. issued Mar. 18, 1997 disclosesspontaneously wettable fibers having a combination of X values andsurface contact angles that satisfy conditions for spontaneous wetting.The X factor is defined therein as X=P_(w)/(4r+(π−2)D) where P_(w) isthe wetted perimeter of the filament, r is the radius of thecircumscribed circle circumscribing the fiber's cross-section, and D isthe minor axis dimension across the fiber's cross-section. The teachingsof and especially the definitions in the Phillips '981 patent are herebyincorporated herein by reference as if fully set forth herein. Thisspecification discloses values for fibers shown in examples herein forsome of the quantities defined in the Phillips '981 patent.

U.S. Pat. No. 5,268,229 to Phillips et al. issued Dec. 07, 1993discloses specific “U” and “E” shaped cross-sections of spontaneouslywettable fibers with stabilizing legs.

U.S. Pat. No. 5,314,743 discloses non-woven webs made from capillarychannel fibers.

U.S. Pat. No. 3,121,040 to Shaw et al. discloses “+” and “Y” shapedpolyolefin fibers with arm length/arm width ratios greater than 4. Thesefibers are so thick and large that they are too stiff for use inconsumer disposables. The smallest arm width disclosed in the Shaw etal. patent is about 75 microns.

International patent application PCT/US95/08896 discloses a structurethat is capable of transporting liquids by intercapillary action usingessentially parallel fibers, and discloses that the driving force on theliquid is directed from the open areas to the closed areas.

U.S. Pat. No. 4,829,761 to Phillips et al. issued May 16, 1989 disclosescontinuous filament yarns. The teachings of and especially thedefinitions in that patent are hereby incorporated herein by referenceas if fully set forth herein. This specification provides values forfibers shown herein for the specific volume quantity defined in thePhillips '761 patent, U.S. Pat. No. 4,245,001 to Phillips et al. alsodiscloses the specific volume quantity, and its teachings are alsoincorporated by reference as if fully set forth herein. The specificvolume is defined in the Phillips '761 patent in units of cubiccentimeters per gram as 8.044 divided by the weight of the yarn in gramswhen the yarn is under a tension of 0.1 grams per denier for a volume ofyarn filling an 8.044 cubic centimeter volume. Thus, the specific volumeis the volume per gram of material in a volume of space when the fibersof the yarn are pressed against one another in the volume of space andare under a defined tension.

Much of the interest in polymer structures that absorb and transportliquid is because of their applicability in consumer disposableproducts. The inventors view absorbent cores of modern consumerdisposable products including diapers, adult incontinent pads, andfeminine napkins, as having three primary functions; acquisition,distribution, and storage of liquids. The distribution function istypically poorly executed with current absorbent core components such asfluff pulp and/or super absorbent polymer. As a consequence, excessiveleakage and poor utilization of the absorbent core material relative tothe theoretical maximum absorbent capacity of the absorbent corematerial are problems limiting the performance of these consumerdisposables.

Poor distribution occurs because the components of the core aretypically good at storing liquids but poor at distributing them. Manyattempts have been made in the prior art to solve this problem.

International Patent Application No. WO 95/00093 dated Jan. 05, 1995discloses a sanitary pad with a liquid directing strip and an absorbentstrip positioned under a top sheet.

U.S. Pat. No. 5,342,336 to Meirowitz et al. issued Aug. 30, 1994 anddiscloses a structure for absorbing and transporting a liquid thatincludes shaped staple fibers to move liquids more toward the ends ofthe pad. Typically, staple fibers are less than two inches long.

U.S. Pat. No. 4,324,247 to Aziz issued Apr. 13, 1982 and discloses anabsorbent article including a top sheet, an absorbent core, and aperforated thermoplastic film between the top sheet and the absorbentcore. The Aziz patent teaches that its structure prevents liquid in thecore from flowing out of the absorbent core back to the top sheet whenthe structure is squeezed.

U.S. Pat. No. 4,321,924 to Ahr issued Mar. 30, 1982 and discloses anabsorbent article including a top sheet, a layer of fibers affixed tothe inner surface of the top sheet, the fiber layer overlaying anintermediate layer having a multiplicity of tapered capillaries, and anabsorbent core. The Ahr patent asserts that the Ahr structure providesimproved acquisition and reduced re-wetting.

United Kingdom Patent Application GB 2,225,724A was published Jun. 13,1990 and discloses an absorbent device that includes a liquid perviouscover sheet, an absorbent core, and a liquid pervious intermediate layerthat is between the absorbent core and the cover sheet and that hasapertures and contours. This patent application asserts that itsstructure provide reduced re-wetting.

U.S. patent application Ser. No. 545,450 filed Oct. 19, 1995 disclosesan apertured film with cut out portions in the apertured walls toprovide spontaneous liquid inversion from the front side of the topsheet to the backside of the top sheet. The teachings of the '450application are hereby incorporated by reference as if fully set forthherein and may be used in conjunction with the absorbent productinventions defined herein.

Thus, there is a general ongoing desire in the art to increase theabsorbent capacity and the liquid transport capacity of polymer materialfor various applications. There is a more specific continuing need inthe art for a family of acquisition/distribution structures which canbetter transport and distribute liquids in disposable absorbentproducts. Accordingly, it is to the provision of such that the presentinvention is primarily directed.

Further, it is to be understood that the inventors conceive ofadditional applications relating to the novel transport ability of thebasic fiber structures disclosed herein including filtering of liquidsand suspensions, horizontal transport of liquids, and vertical transportof liquids.

SUMMARY OF THE INVENTION

The invention is a bundle of synthetic fibers for transporting fluids.The bundle comprises at least two fibers that when acting as individualfibers are poor transporters of fluids, yet when in a bundle the fibersprovide a bundle that is an excellent transporter of fluids. The bundlesare useful in absorbent articles such as diapers, incontinents andfeminine hygiene products.

The bundle has a Specific Volume greater than 4.0 cubic centimeters pergram (cc/gm), an average inter-fiber capillary width of from 25 to 400microns, and a length greater than one centimeter (cm). Preferably, thefluid to be transported is aqueous and the movement of fluid in thebundle is measured according to the following parameters as definedherein: a MPF_(B)/MPF_(SF) greater than or equal to 3.0, a MPF_(B)greater than or equal to 0.14 cubic centimeters per denier per hour(cc/(den*hr)), a VR_(B)/VR_(SF) greater than or equal to 1.3, and aVR_(B) greater than or equal to 4.0 centimeters (cm).

At least one of the two fibers has a non-round cross-section, a SingleFiber Bulk Factor greater than 4.0, a Specific Capillary Volume lessthan 2.0 cc/gm or a Specific Capillary Surface Area less than 2000 cc/gmand more than 70% of intra-fiber channels having a capillary channelwidth greater than 300 microns. Preferably, the cross-section defines afirst arm having a length greater than 40 microns. The lengths of thecross-section of the fibers range up to almost 1000 microns with some ofthe examples having arm lengths that are between 100 and 400 microns.Preferably, the fibers have a denier (den) between 15 and 250. Thecross-section and the surface composition of the non-round fiberspreferably satisfy the inequality: (Pγ cos(θa))/d>0.03 dynes/den,wherein P is the perimeter of the cross-section of the fiber, γ is thesurface tension of the liquid, (θa) is the advancing contact angle ofthe liquid measured on a flat surface made from the same material as thefiber and having the same surface treatment and d is the denier of thefiber.

Further, the invention includes the novel spinnerettes used to make thefibers of the bundles. Those spinnerettes are characterized by verylarge ratios of the length to the width of the aperture of thespinnerette and large absolute lengths of sections of the aperture ofthe spinnerette. Preferably, the length to width ratios of a section ofthe spinnerette is greater than 40, more preferably greater than 60, andeven more preferably greater than 100. The length to width ratio ofindividual cross-section segments (e.g., legs, arms) may be between 40and about 150.

Further, the process of making the fibers of the present inventionincludes heating the polymer to between 270° and 300° centigrade andextruding the heated polymer through an aperture having a width of lessthan 0.12 millimeters (mm) and a total length of at least 50 times thewidth.

Further, liquid acquisition,distribution structures are included in theinvention which comprise a top layer that is permeable to a liquid, adistribution layer, and a resistance layer. The distribution layercomprises a capillary system providing capillary forces on the liquidwhen the liquid is in contact with the distribution layer tending totransport the liquid parallel to the top layer. The resistance layer hasa resistance layer top surface and a resistance layer bottom surface.The resistance layer provides resistance to transmission of the liquidfrom the resistance layer top surface to the resistance layer bottomsurface. An absorbent core may also be added to the structures which maybe beneath the resistance layer or partially surrounded by thedistribution layer and the resistance layer.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a schematic identifying relative dimensions of an aperture ofa spinnerette used in example 1;

FIG. 1B is a partial sectional view showing a bore detail for theaperture of the spinnerette of FIG. 1A;

FIG. 1C is a plan view of an interior face of the spinnerette used inexample 1 showing a bore and aperture pattern;

FIG. 2 is a photocopy of a photograph at a magnification of 156 ofcross-sections of the fibers of example 1;

FIG. 3A is an engineering diagram in plan showing the relativedimensions of an aperture of a spinnerette used in example 2;

FIG. 3B is a partial sectional view showing a bore detail for theaperture of the spinnerette shown in FIG. 3A;

FIG. 3C is a plan view of an interior face of the spinnerette used inexample 2 showing a spinnerette aperture pattern;

FIG. 4 is a photocopy of a photograph at a magnification of 162 ofcross-sections of fibers of example 2;

FIG. 5A is a partial sectional view of a bore for an aperture of aspinnerette used in example 3;

FIG. 5B is a schematic view of a bore and an aperture of a spinneretteused in example 3;

FIG. 5C is a schematic identifying relative dimensions of an aperture ofa spinnerette used in example 3;

FIG. 5D is a plan view of an interior face of the spinnerette used inexample 3 showing a bore and an aperture pattern;

FIG. 6 is a photocopy of a photograph at a magnification of 158 ofcross-sections of the fibers of example 3;

FIG. 7A is a partial sectional view showing a bore detail for anaperture of a spinnerette used in example 4;

FIG. 7B is a plan view of a bore and an aperture of the spinnerette usedin example 4;

FIG. 7C is a schematic identifying relative dimensions of an aperture ofthe spinnerette used in example 4;

FIG. 7D is a plan view of an interior face of the spinnerette used inexample 4 showing a bore and an aperture pattern;

FIG. 8 is a photocopy of a photograph at a magnification of 158 of across-section of a fiber of example 4;

FIG. 9A is a partial sectional view showing a bore detail for anaperture of a spinnerette used in example 5;

FIG. 9B is a plan view of a bore and an aperture of the spinnerette usedin example 5;

FIG. 9C is a schematic identifying the relative dimensions of anaperture of the spinnerette used in example 5;

FIG. 9D is a plan view of an interior face of the spinnerette used inexample 5 showing a bore and an aperture pattern;

FIG. 10 is a photocopy of a photograph at a magnification of 163 of across-section of a fiber of example 5;

FIG. 11A is a partial sectional view showing a bore detail for anaperture of a spinnerette used in example 6;

FIG. 11B is a plan view showing a bore and an aperture of thespinnerette used in example 6;

FIG. 11C is a schematic showing the relative dimensions of an apertureof the spinnerette used in example 6;

FIG. 11D is a plan view of an interior face of the spinnerette used inexample 6 showing a bore and an aperture pattern;

FIG. 12 is a photocopy of a photograph at a magnification of about 190of a cross-section of a fiber of example 6;

FIG. 13A is a partial sectional view showing a bore detail for anaperture of a spinnerette used in example 7;

FIG. 13B is a plan view of a bore and an aperture of the spinneretteused in example 7;

FIG. 13C is a schematic showing the relative dimensions of an apertureof the spinnerette used in example 7;

FIG. 13D is a plan view of an interior face of the spinnerette used inexample 7 showing a bore and an aperture pattern;

FIG. 14 is a photocopy of a photograph at a magnification of about 130of a cross-section of a fiber of example 7;

FIG. 15A is a partial sectional view of a bore detail for an aperture ofa spinnerette used in example 8;

FIG. 15B is a plan view showing a bore and an aperture of thespinnerette used in example 8;

FIG. 15C is a schematic identifying the relative dimensions of theaperture of the spinnerette used in example 8;

FIG. 15D is a plan view of an interior face of the spinnerette used inexample 8 showing a bore and an aperture pattern;

FIG. 16 is a photocopy of a photograph at a magnification of about 230of a cross-section of a fiber of example 8;

FIG. 17A is a partial sectional view of a bore detail for an aperture ofa spinnerette used in example 9;

FIG. 17B is a plan view of a bore and an aperture of the spinneretteused in example 9;

FIG. 17C is a schematic showing the dimensions of the aperture of thespinnerette used in example 9;

FIG. 17D is a plan view of an interior face of the spinnerette used inexample 9 showing a bore and an aperture pattern;

FIG. 18 is a photocopy of a photograph at a magnification of about 87 ofa cross-section of a fiber of example 9;

FIG. 19A is a schematic of a fiber cross-section of prophetic example 10showing generalized dimensions of the cross-section;

FIG. 19B is a schematic of fiber cross-section of prophetic example 10which will result from the spinnerette aperture shown in FIG. 19C;

FIG. 19C is a plan view of an aperture of a spinnerette of propheticexample 10;

FIG. 20 is a schematic of a fiber cross-section showing generalizeddimensions for the cross-section of a fiber of example 3;

FIG. 21A is a schematic of a fiber cross-section of prophetic example 11showing the generalized dimensions of the cross-section;

FIG. 21B is a schematic plan view of the shape of a spinnerette aperturethe use of which will result in a fiber having the cross-section shownin FIG. 21C;

FIG. 21C is a schematic of a fiber cross-section of prophetic example 11which will form when using the spinnerette aperture shown in FIG. 21B;

FIG. 21D is a schematic plan view of an aperture of a spinnerette foruse in prophetic example 11 which will produce a fiber whose shape issimilar to the shape shown in FIG. 21A with all of the θ angles being90°;

FIG. 21E is a plan view of an aperture of a spinnerette for propheticexample 11 which will produce a fiber whose shape is similar to theshape shown in FIG. 21A with all of the θ angles being 90°;

FIG. 21F is a schematic plan view of an aperture of a spinnerette forprophetic example 11 which will produce a fiber whose shape is similarto the shape shown in FIG. 21A with all of the θ angles being 90°;

FIG. 21G is a plan view of an aperture of a spinnerette for propheticexample 11 which will produce a fiber whose shape is similar to theshape shown in FIG. 21A with all of the θ angles being 90°;

FIG. 22A is a schematic of a cross-section of a fiber showinggeneralized dimensions of cross-sections of the fibers of example 5;

FIG. 22B is a schematic of a cross-section of a fiber having thegeneralized shape of fibers of example 5 and that will result from thespinnerette aperture shown in FIG. 22C;

FIG. 22C is a schematic of an aperture of a spinnerette the use of whichwill result in a fiber having the cross-section shown in FIG. 22B;

FIG. 23 is a schematic of a cross-section of a fiber having thegeneralized shape of fibers of example 6;

FIG. 24 is a schematic of a cross-section of a fiber having thegeneralized shape of fibers of example 8;

FIG. 25 is a schematic of a cross-section of a fiber of the inventionshowing additional features in the cross-sections of fibers of theinvention;

FIG. 26A is a schematic of a cross-section of a fiber for use inillustrating the definition of the single fiber bulk factor;

FIG. 26B is a schematic of a cross-section of a fiber for use inillustrating the definition of the single fiber bulk factor;

FIG. 27 is a schematic illustrating an image analysis system for use inmeasuring properties of fibers;

FIG. 28 is a schematic plan sectional view along an axis of a liquiddispensing tip of the imaging system of FIG. 27;

FIG. 29 is a schematic side view of the liquid dispensing tip of FIG.28;

FIG. 30A is a schematic showing the dimensions of an aperture of aspinnerette used in comparative example 12;

FIG. 30B is a schematic illustrating a face of the spinnerette used incomparative example 12 showing an arrangement of bores and apertures;

FIG. 31 is a photocopy of a photograph at a magnification of about 270of a cross-section of comparative example 12;

FIG. 32A is a partial side sectional view of the bore for an aperture ofthe spinnerette used in example 13;

FIG. 32B is a schematic plan view of a bore and an aperture of thespinnerette used in example 13;

FIG. 32C is a schematic showing the dimensions of an aperture of thespinnerette used in example 13;

FIG. 32D is a plan view of an interior face of the spinnerette used inexample 13 showing a bore and an aperture pattern;

FIG. 33 is a photocopy of a photograph at a magnification of about 420of a cross-section of a fiber of example 13;

FIG. 34 is a photocopy of a photograph of a cross-section at amagnification of about 330 of a cross-section of a fiber of example 14;

FIG. 35 is a schematic of a cross-section of a fiber used forillustrating the determination of capillary channel area for flow forcross-sections having channels having essentially parallel channel wallsseparated by less than 150 microns;

FIG. 36A is a schematic of a cross-section of a fiber useful forillustrating the determination of capillary channel area for flow forfiber cross-sections having walls defining channels separated by greaterthan 150 microns;

FIG. 36B is a schematic of a cross-section of a fiber useful for flowfor illustrating determination of capillary channel area for flow forlarge channels;

FIG. 36C is a schematic of a cross-section of a fiber useful forillustrating determination of capillary channel area for flow for largechannels having a long wall and a short wall;

FIG. 37A is a schematic of a cross-section of a fiber useful forillustrating the determination of the capillary channel area for flowfor “V” shaped channels whose channel walls define an angle of less than1200 and have widths at the mouths of less than 150 microns;

FIG. 37B is a schematic of a cross-section of a fiber useful forillustrating the determination of capillary channel area for flow forchannels whose walls define an angle of less than 1200 and which have awidth at the mouth of greater than 150 microns;

FIG. 37C is a schematic of a cross-section of a fiber useful inillustrating the determination of capillary channel area for flow forchannels whose walls define an angle of less than 120°, which have awidth at the mouth greater than 150 microns, and which have one channelwall shorter than the other channel wall;

FIG. 38A is a schematic of a cross-section of a fiber useful inillustrating the determination of single fiber bulk factor;

FIG. 38B is a schematic of a cross-section of a fiber useful inillustrating the determination of single fiber bulk factor;

FIG. 39 is a schematic illustrating a metal/plastic harp having loops offibers tied there around that is useful in illustrating thedetermination of vertical rise;

FIG. 40A is a schematic side sectional view of a basic liquidacquisition/distribution structure of the present invention;

FIG. 40B is a schematic side sectional view of an absorbent product ofthe invention showing the distribution of the liquid in theacquisition/distribution structure between the cover sheet and theabsorbent core;

FIGS. 41A-C are top views of various alternative embodiments of thebasic liquid acquisition/distribution structures of FIGS. 40A-40Bshowing different liquid distribution structures;

FIGS. 42A-D are graphical representations of the distribution of liquidflow into various layers of the absorbent product of the invention;

FIGS. 43A-B are side sectional views of the acquisition/distributionstructure and absorbent core showing embodiments of the communication ofthe channels or grooves in the distribution layer with the absorbentcore;

FIG. 44A is a top plan view of a liquid acquisition,distributionstructure of the invention used in examples 15-22;

FIG. 44B is a side sectional view of the acquisition/distribution systemof FIG. 44A;

FIG. 45A is a photocopy of a photograph of a magnified cross-section ofa fiber bundle of example 15;

FIG. 45B is a photocopy of a photograph of a magnified cross-section ofa fiber bundle of example 18;

FIG. 45C is a photocopy of a photograph of a magnified cross-section ofa fiber bundle of example 19;

FIG. 45D is a photocopy of a photograph of a magnified cross-section ofa fiber bundle of example 20;

FIG. 46A is a photocopy of a photograph of a magnified cross-section ofa fiber bundle of example 21;

FIG. 46B is a photocopy of a photograph of a magnified cross-section ofa fiber bundle of example 22;

FIG. 47A is a top plan of a liquid acquisition/distribution structureused in example 28;

FIG. 47B is a side sectional view of a liquid acquisition/distributionstructure used in example 28;

FIG. 48 is a side view of an alternative embodiment of the liquidacquisition/distribution structure of the present invention;

FIG. 49 is a side view of another alternative embodiment of a liquidacquisition/distribution structure of the present invention;

FIG. 50 is a top view of yet another alternative embodiment of a liquidacquisition/distribution structure of the present invention;

FIG. 51A is a schematic top plan view of an absorbent article of example29;

FIG. 51B is a partial side sectional view of the absorbent article ofexample 29;

FIG. 52 is a photocopy of a photograph of the fiber retaining mechanismof FIG. 27;

FIG. 53 is a photocopy of a photograph of a video image;

FIG. 54 is a schematic of a histogram of image pixel intensity versusnumber of pixels;

FIG. 55 is a photocopy of a photograph of a video image of a region ofinterest at four different times;

FIG. 56 is a photocopy of a photograph of a video image includingvarious data relating to liquid flux calculations;

FIG. 57 is a flowchart showing an overview of algorithms for determiningMPF and V_(O);

FIG. 58 is a flowchart showing an algorithm for setting up for datacollection;

FIG. 59 is a flowchart showing an algorithm for acquiring data;

FIG. 60 is a flowchart showing an algorithm for calculating MPF andV_(O) based upon acquired data;

FIG. 61 is a schematic cross-section of a fiber helpful in defining SCVand SCSA; and

FIG. 62 is a schematic cross-section of a fiber helpful in defining Sand CCW.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is a bundle of synthetic fibers which, whenwetted, is capable of transporting liquid along its length at arelatively large liquid flux as compared to the liquid flux associatedwith an individual fiber in the bundle. In other words, the bundleconsists of fibers which individually are poor liquid transporters orwhich have no “capillary channels” on their surfaces, i.e have nointra-fiber capillary channels. This unexpected improved liquidtransport that the bundles provide over the individual fibers that arepoor liquid transporters is a phenomenon resulting from a novelcombination of fiber and bundle structure, which create inter-fibercapillaries, and surface composition of the fibers.

The term “capillary channels” as used herein refers to prior artdefinitions of this term wherein channels having a width of about lessthan 300 microns, preferably 250 microns, are considered capillarychannels since the capillary forces acting within the channels are muchgreater than the force of gravity.

Bundle Structure

As used herein, the term “bundle” refers to two or more syntheticfibers, preferably 8 to 50,000 fibers, that have a length greater thanone centimeter, are aligned on the average parallel with one another andhave inter-fiber capillaries. An average inter-fiber capillary width, D,of the bundles of fibers is about 25 to 400 microns, preferably 60 to300 microns and more preferably 100 to 300 microns. The averageinter-fiber capillary width, D, is defined by the following equation:${D = \frac{4\left( {{SV} - {1/\rho_{P}}} \right)*{dpf}*10^{3}}{9P}};$

wherein SV is the Specific Volume of the bundle of fibers (cc/gm), ρ_(P)is the density of the polymer from which the fiber is made (gm/cc), dpfis the average denier (den) of the individual fiber (gms/9000 meters ofa single fiber) and P is the average perimeter of the cross-section ofthe individual fibers (microns).

Sv is measured using the procedure described in U.S. Pat. No. 4,829,761except that the tension used to define SV herein is 0.05 gm/den insteadof the 0.10 gm/den for the '761 patent. The bundle is wound at aspecified tension of 0.05 grams/den into a cylindrical slot of knownvolume (normally 8.044 cc). The bundle is wound until the known volumeof the slot is completely filled by winding of the bundle. The weight ofthe bundle contained in the slot is determined to the nearest 0.1milligram (mg). The specific volume is then defined as the ratio of theknown volume to the weight of the bundle in the slot, which may berepresented as${{SV}\left( {{at}\quad 0.05\quad {{gm}/{den}}\quad {tension}} \right)} = {\frac{8.044\quad {cc}}{{wt}\quad {of}\quad {yarn}\quad {in}\quad {gms}}.}$

The bundle of synthetic fibers of the invention provide the followingtwo properties:

1. MPF_(B)>0.14 cc/(den*hr)

and ${2.\quad \frac{{MPF}_{B}}{{MPF}_{SF}}} \geq 3$

wherein Maximum Potential Flux (MPF) is a measure of maximum volume ofliquid transported per denier of the fiber (or fibers) forming thecapillary (or capillaries) per unit of time. All MPF values in thisapplication are in units of cubic centimeters per denier per hour(cc/(den*hr)). The test liquid utilized in the measure of MPF for datain this specification must be either (1) Syltint® Red Fugitive Tint,commercially available from Milliken Chemical, a division of Milliken &Company of Inman, S.C. or (2) Red Test Solution as described in detailbelow. Both test liquids are dark colored aqueous solutions which makethem visually observable. Syltint Red has a surface tension of about 54dynes/cm and a shear viscosity of about 1.5 centipoise. Red TestSolution has a surface tension of about 54 dynes/cm and a shearviscosity of about 1.5 centipoise. Shear viscosity is measured at 25° C.using a Cannon-Ubbelohde Calibrated Viscometer. The procedure forobtaining MPF values is discussed in detail below.

MPF is a quantity that indicates the effectiveness of a fiber or abundle of fibers in transporting liquid per weight of the fibers. Thesubscript “SF” refers to the MPF of a single fiber. The subscript “B”refers to the MPF of a bundle of fibers. The MPF values are based uponthe net liquid flux propagating along both directions of the fiber orbundle of fibers. Because the flux is a property in one direction, thereis a factor of two appearing in the definition of MPF to account for themovement of liquid in both directions away from where it contacts thebundle. This is sometimes referred to as “two-way” MPF to emphasize thefactor of two in the definition. Thus, MPF_(B) means MPF for a bundle offibers, and MPF_(SF) means MPF for a single fiber (i.e., a filament).

The MPF_(B)/MPF_(SF) ratio refers to the MPF_(SF) for a single fiberthat is essentially identical (i.e., having the same surface morphologyshape and the same composition) as fibers forming the bundle having theMPF_(B). A bundle may be formed from fibers having different shapedcross-sections. For such a bundle that is formed from fibers havingdifferent shaped cross-sections, an effective MPF_(B)/MPF_(SF) ratio canbe calculated by averaging the MPF_(SF) values for the fibers formingthe bundle and using the averaged value for MPF_(SF) in the ratio forMPF_(B)/MPF_(SF). Reference hereinafter to the MPF_(B)/MPF_(SF) ratioincludes the effective ratio for bundles formed from fibers havingdifferent shaped cross-sections.

For a bundle of N fibers, MPF_(B) is defined by the equality:${{MPF}_{B} = {8 \times 10^{- 4}*{Vo}_{N}*{SV}*\left( {1 - \frac{1}{\rho_{P}*{SV}}} \right)}},$

which is in cubic centimeters per denier per hour, wherein N is thenumber of the fibers in the bundle; Vo_(N) is the initial velocity ofthe liquid in the N fiber bundle in millimeters per second (mm/s)measured according to the procedures described below; SV is the specificvolume of the bundle; and ρ_(p) is the density of the polymer formingthe fibers of the bundle (gm/cc). For example, the maximum potentialflux for a bundle of eight fibers is;${{MPF}_{B} = {8 \times 10^{- 4}*{Vo}_{8}*{SV}*\left( {1 - \frac{1}{\rho_{P}*{SV}}} \right)}},$

wherein Vo₈ is the defined quantity called “Initial Velocity” of theliquid moving along a bundle of eight fibers in millimeters per second;SV is the specific volume of the bundle of fibers in cubic centimetersper gram at a tension of 0.05 gm/den, ρ_(p) is the density of thepolymer used to make the fibers of the bundle of eight fibers (gm/cc).All values for MPF_(B) herein are based on Vo for a bundle of eightfibers. The use of a bundle of eight fibers as the basis for measuringVo of the present invention is an arbitrary number. The reason that abundle of eight fibers is used in the procedures for determining MPFrelates to the ease with which liquid transport properties of a bundleof eight fibers and a single fiber can be measured with the sameinstrument, not because a bundle of eight fibers is more effective attransporting liquid than a bundle of a larger number of fibers.

The two-way MPF_(SF) for a single fiber is defined in cubic centimetersper denier per hour as:

 MPF _(SF)=2*0.1620*Vo*(capillary channel area for flow)*1/dpf,

wherein Vo (mm/sec) is the Initial Velocity of the liquid and dpf is thedenier of the single fiber (gm/9000 m). The capillary channel area forflow (microns²) is defined hereinbelow in the discussion of FIGS.35-37C.

The MPF_(B) for embodiments of the present invention ranges from 0.14 to2.0 cc/(den*hr) and preferably from 0.2 to 2.0 cc/(den*hr). Since theMPF_(B) is the movement of fluid along the bundle, the higher this valuethe better. Thus, the value for MPF_(B) which represents bundles offibers of this invention is simply greater than 0.14 cc/(den*hr), morepreferably greater than 0.2 cc/(den*hr). The examples disclosed hereinhave MPF_(B) for eight fiber bundles of between about 0.06 and about0.36. The ratio of MPF_(B)/MPF_(SF) is from 3 to 28. Preferably theratio is greater than 5 and more preferably greater than 11.

Another measure of the properties of the bundles of synthetic fibers isthe ratio of the height of the vertical rise of the test liquid, i.e.Syltint® Red or Red Test Solution, up along the bundle from a reservoirof the test liquid and against the pull of gravity to the height of thevertical rise of the test liquid up along a single fiber of the sametype of fibers as the fibers forming the bundle and against the pull ofgravity. The vertical rise measurement for a bundle of fibers of thepresent invention satisfies the inequality:${\frac{{Vertical}\quad {Rise}\quad ({Bundle})}{{Vertical}\quad {Rise}\quad \left( {{Single}\quad {Filter}} \right)} \geq 1.3},$

wherein Vertical Rise (VR) means the distance the test liquid risesabove the level of the liquid to which the fiber or the bundle of fibersis in contact. Vertical Rise is reported herein in centimeters (cm) fora period of fifteen minutes unless otherwise specified. The ratioVR_(B)/VR_(SF) is from 1.3 to 11.7, preferably greater than 2 and morepreferably greater than 2.3. VR_(B) is preferably greater than 4 cm andVR_(SF) is preferably less than 4 cm.

The length of the bundle depends upon the length of liquid transportrequired for the desired application. Preferably, the bundle is at leastone centimeter long. More preferably, the bundle is at least fivecentimeters long. For diapers, feminine napkins, and incontinent pads,the desired liquid transport lengths range from about 5 centimeters toabout 40 centimeters. The bundle length is usually about twice themaximum transport length over which it is intended that the liquid betransported. This is because the liquid insults are designed to be nearthe centers of most absorbent products.

Preferably, when the bundle is wetted, at least one half of the fibersof the bundle contact at least one other fiber of the bundle on anaverage of at least once per centimeter. More preferably, when thebundle is wetted, each of the fibers of the bundle contact at least oneother fiber of the bundle on an average of at least once per centimeter.

Preferably, tangents to the longitudinal axis of each of the fibers of abundle are within 30° to one another along at least one half the lengthof the bundle. However, bundles of fibers that split at some point intotwo or more bundles that are not aligned with one another but otherwisemeet the criteria indicated above are within the scope of thisinvention.

To ensure contact between fibers of the bundle when the bundle is notwetted, the fibers may be held together by a slight stickiness resultingfrom an anti-static or a hydrophilic finish if such a finish is present,by a crimp in the fiber that mechanically constrains the fibers of thebundle relative to one another, or merely by the placement of the fibersaligned adjacent one another when there are no substantial attractive orrepulsive forces on the fibers of the bundle.

The fibers of the bundle do not necessarily have a uniquecross-sectional orientation relative to one another. That is, since thefibers of the bundle are not necessarily rigidly connected to oneanother, there may be rotations of the cross-sections or localmisalignments of the fibers along their lengths. Their orientationsrelative to one another along their length may be random or the bundlesmay be minimally twisted. There is no requirement of a fixed spatialrelationship between the fibers of the bundle when the bundle is notwetted in order to provide the large liquid flux when the bundle iswetted. Thus, any bundle of fibers pressed against one another thatprovides an average inter-fiber capillary width of from 25 to 400microns and has a specific volume greater than 4.0 cc/gm is within thescope of the present invention.

For purposes of further explaining the invention, one idealizedstructure is a bundle of fibers that when wetted and thereby pressedtogether define (at least) one inter-fiber capillary channel that hasparallel walls, in which the inter-fiber capillary channel's walls arespaced from one another by the average inter-fiber capillary widthsindicated above due to some sort of standoff structure, and in which thestandoff structure is part of the cross-section of at least some of thefibers of the bundle.

Fiber Structure

The individual fibers of the present invention are shaped fibers havingthin armed cross-sections. The term “shaped” fibers means fibers withnon-round cross-sections. A single fiber has at least one channel thathas walls defined by line segments of the cross-section of the fiber.The channel width of a channel of a single fiber is the length of a linesegment tangent to the distal tips of the channel walls. The majority ofthe channel widths are preferably greater than 300 microns, which isrelatively large as compared to channel widths for fibers of the priorart classified as having intra-fiber capillary channels.

The line segments of the cross-section, which define the channel walls,may be adjacent planar sections that in cross-section are aligned atgreater than 60°, greater than 90°, or even greater than 120° relativeto one another. For example, the planar sections may create a channelhaving two walls which join one another at a “V” shaped intersection ormay also include a base region to which proximal ends of the two wallsjoin. Moreover, the surface of the channel may be curved and thereforehave no planar section defining a channel wall.

A quantitative measure of the deviations of the cross-section of asingle fiber from round is known as the shape factor. The single fibershape factor is a dimensionless ratio defined as:

Shape factor=P/(4πA _(F))^(½)

wherein

A_(F)=area of the fiber's cross-section and

P=the perimeter of the cross-section of the fiber.

The shape factor for the single fibers of the present invention is equalto or greater than 2.0, preferably greater than about 5.0. The shapefactor can be measured by hand from photomicrographs of cross-sectionsor it can be determined automatically by several commercially availablecomputer controlled optical microscope systems. The shape factor of around cross-section fiber is 1.

Another property of the shaped fiber is a measure of the ratio of voidareas formed by the cross-section of a shaped fiber to the polymer areaof the cross-section of the shaped fiber. This property is referred toherein as the single Fiber Bulk Factor (SFBF), which is equal to orgreater than 4 and preferably from 4 to 10. SFBF is defined as:${SFBF} = \frac{{Sum}\quad {of}\quad {the}\quad {void}\quad {cross}\text{-}{sectional}\quad {areas}}{{Fiber}\quad {Cross}\text{-}{sectional}\quad {Area}}$

The void areas are illustrated in the fiber cross-sections of FIGS.26A-B and 38A-B along with exemplary calculations of the SFBF for thecross-sections shown in FIGS. 26A-B. As with shape factor, the singlefiber bulk factor can be determined by hand or using an automatedmeasurement system.

Additional properties of the single fibers of a bundle of the inventionthat characterize the fibers' poor liquid transport properties include aMPF_(SF) equal to or less than 0.03 cc/(den*hr) and a VR_(SF) equal toor less than 4.0 cm. Calculations of these properties are discussedabove.

Being poor liquid transporters, the single fibers of the inventionpreferably do not have intra-fiber capillaries. As used herein,intra-fiber capillaries means channel widths of less than 300 microns.The fibers' structures are such that a bundle of the fibers formsinter-fiber capillaries which create the large liquid fluxes. Forexample, single fibers of the bundles of the invention have an MPF_(SF)less than about 0.03 cc/(den*hr) and a VR_(SF) of less than about 4centimeters in fifteen minutes. When these fibers define bundles of theinvention, the bundles can have an MPF_(B) of greater than 0.2cc/(den*hr) and vertical rise of liquid of over six centimeters (after15 minutes).

Prior art fibers having intra-fiber capillaries that effectivelytransport liquid on their surface meet the criteria set forth in U.S.Pat. No. 5,200,248 (the '248 patent). The fibers of the '248 patent,which individually act as excellent liquid transporters, have thefollowing properties: Specific Capillary Volume (SCV) of at least 2.0cc/gm, Specific Capillary Surface Area (SCSA) of at least 2000 cm²/gm,Compressive Strength Dry of at least 13,800 dynes/cm², Slenderness Ratioof at least about 9, and at least 30 percent of the capillary channels(i.e. intra-fiber capillaries) have a Capillary Channel Width (CCW) ofless than about 300 microns. Fibers that have no intra-fiber capillariesare individually poor liquid transporters and are outside the scope ofthe '248 patent.

However, the fibers of the present invention that do not haveintra-fiber capillaries and are individually poor liquid transporters,are unexpectedly excellent transporters of liquid if in the form of abundle of such fibers comprising at least two individual fibers. Thus,the individual fibers of the present invention which do not haveintra-fiber capillaries may be characterized as non-capillary channelstructures and have the following properties: (1) either SpecificCapillary (channel) Volume less than 2.0 cc/gm or Specific Capillary(channel) Surface Area less than 2000 cm²/gm and (2) more than 70% ofintra-fiber capillaries (channels) having a channel width greater than300 microns.

The following procedures are useful for determination of parameters usedto define and evaluate the capillary channel structures, and are takenverbatim from U.S. Pat. No. 5,200,248 at column 27 line 45 to column 30line 12 and column 35 line 63 to column 35 line 59.

The procedures may require preparation of structures of varying lengths,some of which may exceed the length of the structure actually intendedfor use. It is to be understood that any structures shorter than lengthsrequired by the procedures are evaluated on the basis of equivalentstructures having the requisite lengths set forth in such procedures,except as may be otherwise specifically provided. Specific units may besuggested in connection with measurement and/or calculation ofparameters described in the procedures. These units are provided forexemplary purposes only. Other units consistent with the intent andpurpose of the procedures can be used.

The procedure used to determine Specific Capillary Surface Area (SCSA)and Specific Capillary Volume (SCV) of a capillary channel structure isapplied to a photo-micrograph which shows a representative cross-sectionof the capillary channel structure. The cross-section of the structureis prepared for photomicrographing by embedding and microtomingtechniques known to those skilled in the art. The following equationsare used:

SCSA=sum over x=1to i,of P _(x) /ρA _(s,)  (1)

SCV=sum over x=1to i,of Av _(x) /ρA _(s,)  (2)

wherein:

ρ=density of the solid (i.e., polymer);

A_(S)=area of the cross-section of capillary channel solid perpendicularto the capillary channel axis which bounds those capillary channelswithin the scope of criterial (a) and (b),

the sum over x=1 to i of P_(x)=the sum of the perimeters of the crosssection of the solid forming each of the capillary channels, x, whereineach perimeter P_(x) bounds the capillary channel and is within thetheoretical closure provided by C_(x);

the sum over x=1 to i of Av_(x)=the sum of the, void areas of thecapillary channel structure wherein each Av_(x) is calculated as thearea bounded by the perimeter of the solid forming the channel and byC_(x); and

wherein i is the number of capillary channels in the structure, x refersto specific capillary channels of a capillary channel structure, andC_(x) corresponds to that part of a circle which is convex toward theinterior of the channel and which is of a selected diameter that closeseach capillary channel, x, wherein the circle, C_(x) is sized andpositioned according to the following criteria:

(a) the circle, C_(x), is tangent to both walls of the capillarychannel, x, at the points where it meets the walls; and

(b) for each capillary channel, x, the circle C_(x) meeting (a)maximizes Av_(x) for each such channel, x, subject to the limitationsthat:

(i) the lines tangential to the intersection of C_(x) and the capillarychannel walls intersect to form an angle of 120° or less; and

(ii) C_(x) can have a radius of no greater than about 0.025 cm withrespect to the actual scale of the capillary channel structure (circleradius will be enlarged by the same magnification factor applied to theactual structure in the photomicrograph).

For capillary channel structures having capillary channel wall fluidexchange orifices, the effect on SCV and SCSA will generally not be ofnumerical significance due to the thin walls of the capillary channelstructures hereof, and can generally be disregarded in the calculations.

For capillary channels having multiple points of tangency with a circleof maximum radius, as provided above, the circle is positioned so as tomaximize cross-sectional area (Av) of the channel. For capillary channelstructures having variation in cross-sectional size or shape, sufficientcross-sections can be evaluated to provide a representative weightedaverage SCV and/or SCSA. If, however, any portion of the structure oflinear length (in the axial direction of the capillary channels) of atleast about 0.2 cm, preferably at least about 1.0 cm, has a SCV and SCSAwithin the claimed ranges hereof, that such structure is said tocomprise a capillary channel structure of the present invention.

For capillary channel sheets, particularly those with capillary channelbases of relatively large width, a representative sample of the producthaving a fraction of the total width of the base can be substituted inplace of the entire cross-section of the sheet. Such fractional sampleof the sheet preferably has a width of at least about 0.5 cm. Thepurpose of SCV and SCSA, as defined above, is to provide quantitativeanalysis of structures characterized by open capillary channels. It isconceivable that such structures can have solid portions, appendages,and the like, which do not otherwise contribute to the definition of thecapillary channels in this procedure. The above criteria will excludeperimeter and void areas corresponding to such nonfunctional portions ofthe structure from the calculations. Also, the cross-sectional area ofnonfunctional solid elements is not to be included in the calculation ofA_(s). Exclusion of such perimeters and cross-sectional area isexemplified in more detail below.

FIG. 61 exemplifies a capillary channel structure fragment 800 andapplication of the SCV and SCSA procedure thereto. Shown is the fragment800 of solid (i.e., polymer) having area As, capillary channel voidareas Av₁, Av₂, Av₃, Av₄, with corresponding capillary channelperimeters P₁, P₂, P₃, P₄ and theoretical closure circles C₁, C₂, C₃,and C₄. Also shown are circles C₅, C₆, C₇. Radii r_(1′), r_(1″), r_(2′),r_(2″), r_(3′), r_(3″), r_(4′), r_(4″), r₅, r₆, r₇ are eachperpendicular to the line tangent to the points of intersection m_(1′),m_(1″), m_(2′), m_(2″), m_(3′), m_(3″), m_(4′), m_(4″), m ₅, m₆, m7,respectively, between the corresponding circles, C₁, C₂, C₃, C₄, C₅, C₆,C₇ and the solid material of fragment 800.

The circles C₁, C₂, C₃, and C₄ are drawn so as to meet the abovecriteria. As can be seen circles C₁ and C₂ are limited in radius r₁, r₂by angles γ₁, γ₂ which represent 120° angles of intersection betweentangent lines t_(1′), t_(1″), and between t_(2′), t_(2″), respectively.Av₁, Av₂, Av₃, and Av₄ are the areas bounded by perimeters P₁, P₂, P₃,and P₄ and curves cc₁, cc₂, cc₃, and cc₄, respectively. Circles C₃ andC₄ represent the maximum size circle for capillary channel, wherein theangle of intersection of lines drawn tangent to the circle at pointsm_(3′),m_(3″) and at m₄, and m_(4″), respectively, would be less than120°. Thus, as represented in this exemplary figure, circles C₃ and C₄would each have radius of 0.025 cm, after reduction for magnificationeffects. Perimeters are determined as the length of the solid boundaryinterior to the channels between the points of intersection between thecircle and the solid for each channel. C₅, C₆, and C₇ represent circlesof maximum radius applied to portions of the structure which do notqualify as capillary channels according to the criteria of thisprocedure. Hence, P and Av for these circles would be zero. Asperimeters P₁, P₂, P₃, and P₄, and curves cc₁, cc₂, cc₃, and cc₄, can beseen, the area of the solid between m₄, and m4″ would be included withinA_(s) since such solid corresponds to capillary channel walls boundingchannels within the criteria for Av in the calculation of SCV and SCSA.Areas A_(x3), and A_(x3″), which are bounded by linear extensions of theradii r_(3′), r_(3″), (said radii being perpendicular to the line oftangency between the circle C₃ and the walls of the channel), are notincluded in A_(s). Likewise, radius r₄, truncates area A_(x4) from thecalculation A_(s) based upon extension of r₄, of circle C₄.

Slenderness Ratio (S), Capillary Channel Width (CCW), and AverageStructure Thickness (t_(ave)) are determined according to the proceduresas follow. The procedures are implemented based upon a photomicrographof a representative microtomed cross-section of the capillary channelstructure, as previously described. For capillary channel structureshaving variation in Slenderness Ratio, Capillary Channel Width, andAverage Structure Thickness in the axial direction of the capillarychannels, sufficient cross-sections should be evaluated to provide arepresentative weighted average Slenderness Ratio, Capillary ChannelWidth, and/or average structure thickness value. If, however, anyportion of this structure of linear length in the axial direction of thecapillary channels of at least about 0.2 cm, preferably at least about1.0 cm, has a Slenderness Ratio, capillary channel width, and/or averagestructure thickness value within the ranges hereof, then such structuremay comprise a capillary channel structure of the present invention.Reference is maae to FIG. 62 for exemplary purposes of the procedures.

The following equations are used:

S=L ²/4A _(st)

t _(ave)=2A _(st) /L

wherein:

L=total solid perimeter of the cross-section of the structure; and

A_(st)=total area of the cross-section of the solid forming thestructure perpendicular to the capillary channel axis.

The foregoing equation for Slenderness Ratio treats the fiber underconsideration as if it has one channel-forming wall therein. Forchanneled fibers having a functional portion wherein one or morechannels are present, the formula for Slenderness Ratio (S) can be givenas:

S=L ²/4A _(st) N

wherein;

L and A_(st) as hereinbefore defined; and

N=number of channel walls in the structure, said walls being those thathave, on one or both sides, channels that are closable by straightclosure chords.

CCW is the length of the straight closure chord of a capillary channelwherein said chord closes said intra-structure capillary channel andwhich tangentially contacts the points of intersection with thecapillary channel walls of said channel in such a way to maximize thevolume of the channel. (Portions of the structure which do notcontribute open channels closable by straight closure chords should bedisregarded prior to the above calculations.)

FIG. 62 shows, for exemplary purposes, a cross-section of a capillarychannel structure 900 having chords W1, W2, W3, W4, W5, and W6 forcapillary channels C1, C2, C3, C4, C5, and C6, respectively, thus N=6.FIG. 62 also indicates the region corresponding to total cross-sectionalarea Ast and indicates continuous line P_(L), the length of which is thetotal perimeter L. X_(a)-X_(p) indicate points of tangency of the chordsand the cross-section.

Referring now to FIG. 10, a cross-section of an exemplary fiber of abundle of the present invention is shown which approximates theidealized structure discussed above. This cross-section includes thelong thin channel arms 101A and 101C and short thin channel arm 101B.When a plurality of fibers having the cross-section shown in FIG. 10 arebundled together the long thin channel arms 101A and 101C of adjacentfibers oppose one another and are spaced from one another by thestandoff arms 101B at a distance between 50 and 100 microns (i.e., theinter-fiber average capillary width). Thus, the standoff arms 101B spacethe long thin arms 101A and 101C of adjacent fibers from one another,and the long thin arms 101A and 101C of adjacent fibers that oppose oneanother approximate the idealized parallel inter-fiber capillary channelwalls discussed above. The fact that the long thin arms 101A and 101Care much longer than the inter-fiber average capillary width, D, definesa capillary channel having a length (i.e., parallel to the long arms)that is greater than D. The cross-sections of the fibers having asection (such as an arm or base) extending in one dimension at least thedesired inter-fiber average capillary width indicated above is animportant characteristic of the present invention.

Synthetic fibers of the invention are fibers made from the major meltspinnable groups. These groups include polyesters, nylons, polyolefins,and cellulose esters. Fibers from poly(ethylene terephthalate) andpolypropylene are especially useful at least because of theirmanufacturability and wide range of applications. Preferably, the denierof each fiber is between about 15 and about 250, and more preferablybetween about 30 and 170.

Fiber Surface Composition

The fibers of the bundles of the invention have a surface compositionthat is either hydrophilic or hydrophobic. The surface composition maybe inherent due the nature of the material used to make the fibers ormay be fabricated by application of surface finishes. The type ofsurface finish depends on the nature of the liquid to be transported bythe inter-fiber capillary channels. Hydrophilic surface finishes providestructures the surfaces of which have large adhesion tension (i.e., thatstrongly attract) with aqueous liquids and are therefore preferred forapplications involving aqueous liquids. For absorption, filtering, andtransport applications involving non-polar liquids a hydrophobic surfacefinish is required to provide large adhesion tensions with non-polarliquids.

Preferably, the fibers of the bundle have a hydrophilic surface which isdefined as a surface having an adhesion tension with distilled watergreater than 25 dynes/cm.

Preferably, the fibers of the bundle have a specific surface force whichis mathematically determined by the following equation:

(PγCos (θa))/d≧0.03 dynes/den

wherein P is the perimeter of the cross-section of the fiber; γ is thesurface tension of the liquid on the surface; θ is the advancing contactangle of the liquid on a flat surface having the same composition andfinish as the surface of the fiber (as specified in U.S. Pat. No.5,611,981); γ Cos (θa) is the adhesion tension of the liquid on thesurface of the fiber; and d is the denier of the fiber on which the Pwas measured. Bundles of fibers which satisfy this inequality haveexcellent flow of fluid, whether aqueous or nonaqueous, along the lengthof the bundle.

The surface finishes are typically coated on fibers during theirmanufacture. The coating usually occurs just after the molten polymer isextruded through the aperture of a spinnerette and quenched, but it canbe applied later. The thickness of the coating is much thinner than thecross-section of the fiber and is measured in terms of its percent ofthe total weight of the fiber. The weight percent of the coating istypically between 0.005 and 2.0 percent of the total weight of thefiber.

Some of the finishes,lubricants useful to provide large adhesiontensions to aqueous liquids are described or referenced in U.S. Pat. No.5,611,981. Surface finishes are well known in the art.

Large Liquid Flux

The forces creating the transport of a large flux of liquid along thebundle of the fibers are the result of the surface energetics and thethin armed cross-section shapes of the fibers and relative positions ofthe fibers when wetted, thereby forming the inter-fiber capillaries.When wetted, the bundle of fibers has a large ratio of inter-fibercapillary volume (i.e., void volume) to the volume of the polymer in thefibers forming the bundle. The thinner the cross-sections of the fibers,the larger the ratio of the void volume to the volume of the polymer inthe fibers for a given cross-sectional shape. This ratio may becharacterized by the Single Fiber Bulk Factor or specific volume.

The surface tension of the liquid generates radially directed forces onthe fibers of the bundle that press or collapse the fibers of the bundleagainst one another until the fibers are constrained from further radialcollapse by their cross-sectional shapes. The initial collapse occursvery quickly once the fibers are wetted and results in the fibers of thebundle being in contact with one another along their lengths shortlyafter the bundle is wetted. Thus, as long as the fibers are in contactat any point along their lengths at the time the fibers are wetted, theforces on any two fibers are sufficient to press the fibers against oneanother to form the inter-fiber capillaries.

The flux of a liquid in any capillary is the product of thecross-sectional area of the capillary available for flow times thevelocity of the liquid in the cross-sectional area of the capillary thatis available for flow per mass associated with the channel. For thebundles of fibers to be effective liquid movers, the velocity of theliquid/solid/air front moving from where the bundle is wetted along theaxis of the bundle times the cross-sectional area for flow must berelatively large. The Initial Velocity of liquid along a bundle offibers of the invention synergistically increases with the number offibers from two fibers per bundle to about twelve fibers per bundleafter which there is little change in initial velocity with numbers offibers in the bundle.

The flux of a liquid in any capillary is also dependent on the interplayof the driving force on the liquid in the capillary, the viscous dragforce on the moving liquid, and the gravitational forces on the liquid.The liquid flux is proportional to the driving force divided by viscousdrag force (also known as resistance to flow). The gravitational forceson the liquid affect the liquid flux for capillaries that are notaligned horizontally as is often the case for absorbent product worn byhumans.

The driving force on the liquid in any capillary is proportional to theadhesion tension of the liquid with the surface of the capillary and tothe perimeter of the cross-section of the capillary. Thus, largeradhesion tensions result in larger liquid fluxes. The adhesion tensionof the liquid with the surface of the capillary depends upon thecomposition of the liquid and the composition of the surface of thecapillary. Most conventional hydrophilic surface finishes provide anadhesion tension with aqueous liquids between about twenty and sixtydynes/centimeter. The adhesion tensions with non-polar liquids for mostconventional hydrophobic surface finishes are in the range of ten tothirty dynes/centimeter.

The viscous drag force on the moving liquid in the capillary isapproximately proportional to the viscosity of the moving liquid in thecapillary, the perimeter of the cross-section of the capillary, and thediameter of the capillary. Capillaries that have narrow widths have arelatively large ratio of the perimeter of the cross-section of thecapillary to the cross-sectional area of the capillary resulting inincreased viscous drag force and, thus, reduced liquid flux.

The force of gravity on the liquid in the capillary will affect theliquid flux through the capillary if the capillary is not alignedhorizontally. Because of the gravitational force, the width of avertically aligned capillary that maximizes the liquid flux up to agiven height is narrower than the width of a horizontally alignedcapillary that maximizes the liquid flux.

The average inter-fiber capillary width, D, is the measurement utilizedto determine if the inter-fiber capillaries are sufficiently spacedapart to result in large fluxes. D, as discussed above, is the averagespacing between opposing walls of the inter-fiber capillaries and isbetween 25 and 400 microns. Bundles that have inter-fiber capillarieshaving large capillary cross-section perimeter length percross-sectional area of the capillary and narrow average inter-fibercapillary widths (D), have high resistance to flow. Thus, when wetted,bundles with small Ds must have stronger driving forces percross-sectional area of the inter-fiber capillaries in order to havelarge fluxes. Small inter-fiber capillary widths do not provide themaximum liquid flux because narrow capillaries have smallercross-sections for liquid flow and the viscous drag force inhibits thespeed of the moving liquid.

In view of all of the forces on aqueous liquids, the preferred D for acapillary formed from a polymer structure that is intended to maximizethe liquid flux of aqueous liquids and that has an adhesion tensionprovided by a conventional surface coating is between 50 and 150 micronsfor a capillary in which the liquid must rise up at least threecentimeters and is between 200 and 400 microns for a horizontallyoriented capillary. While it is useful to move liquid up to a height ofthree centimeters in many absorbent products, obviously it is desirableto maximize the liquid flux up to other heights, as well. Thus, D ispreferably between 40 and 120 microns for a polymer structure that isintended to provide a maximal flux up to about six centimeters.

Acquisition/Distribution Structures

Preferably, the bundles of the invention are incorporated into noveldisposable absorbent products such as diapers, adult incontinentproducts, and feminine hygiene products, as a means to internallyacquire and transport liquid in those products.

This invention also includes novel liquid acquisition/distributionstructures for absorbent products that distribute aqueous liquids andare useful in consumer disposable products such as diapers, femininenapkins and incontinent products. The liquid acquisition/distributionstructures acquire and distribute human body liquids, reduce leakage,improve core material utilization by increasing the liquid distributionto regions of the core, which improves dryness of the exterior of theabsorbent product thereby increasing the wearer's comfort.

The acquisition/distribution structures may also be useful for non-polarliquids. For example, absorbent materials are useful for absorbentproducts for cleaning up household or industrial oil spills. Absorbentproducts for cleaning up oils may include an acquisition/distributionstructure of this invention that is tailored for acquiring anddistributing non-polar liquids.

The novel absorbent product of the invention include (1) a liquidacquisition/distribution structure comprising (a) a top layer, (b) adistribution layer and (c) a flow resistance layer that is resistant topenetration in the direction perpendicular to the plane of the fabric,the basic structure of which is shown in FIG. 40A, (2) an absorbent coreand (3) an impermeable back sheet. The liquid acquisition/distributionstructure of the absorbent product of the invention is usually the layer(or layers) directly above the absorbent core containing the liquidstorage material, as shown in FIG. 43B. The core is above theimpermeable back sheet thus completing the absorbent product.

The top layer, also called a top sheet, may be any conventional topsheet material such as perforated polyethylene film or a calendar bondedor a spun bonded top sheet made from polypropylene fiber. However, thetop layer may be made from other perforated polymer films and fibers.Preferably, the underside of the top sheet has a lower contact anglewith aqueous liquids than the top side of the top sheet.

In another preferred embodiment the top sheet is made from an aperturedfilm with cut out portions in the aperture walls to provide spontaneousliquid inversion from the frontside of the top sheet to the backside, asdisclosed in U.S. patent application Ser. No. 545,450 filed Oct. 19,1995.

The distribution layer or structure may be made from any continuouscapillary system such as a capillary sheet, a web, a bundle, or a tow,or filaments that each provide spontaneous transport (or wetting) ofliquids along their surfaces. The capillary system preferably includescapillaries aligned in specific directions. The capillary system mayinclude fiber that each spontaneously transport (or wet) the liquids ofinterest. Preferably, the distribution layer or structure includes abundle of the high MPF_(B) fibers of the type disclosed in examples 1-9.

While not preferred, the distribution layer or structure may be madefrom a large number of round cross-section continuous fibers which arein close proximity to each other, preferably touching one another.Whichever fibers are used in the distribution layer, they defineinter-fiber capillaries that provide for directional flow of liquidalong the aligned direction of the fibers.

Examples of fibers are the spontaneously transporting or wettable fibersdisclosed in U.S. Pat. Nos. 5,268,229, 5,200,248 and 5,611,981 and thebundles of fibers disclosed in this specification. These fibers may bemade in the form of tows, slivers, nonwoven webs, yarns, etc.

The spontaneously transporting fibers are not constrained to be bundledtogether (i.e., in close proximity to each other) in order to transportliquids. However, the spontaneously transporting fibers provide moreflux when they are bundled. Spontaneous wettability and close proximityin this context means that the fibers do not have to form inter-fibercapillaries, since each individual fiber will transport liquid but it isdesirable. Since (1) capillary action is only significant forcapillaries which can generate forces large when compared to the forceof gravity on the liquid and (2) only capillaries with dimensions lessthan about 300 microns do so, close proximity in this context means lessthan about 300 microns. Therefore, spontaneous transporting or wettablefibers in the distribution layer can be more than 300 microns averagespacing from one another.

The directional flow in the distribution layer can be designed byarrangements of the directions of transport of the liquid to be (1)essentially radially outward from a point or small region, (2)essentially bi-directional, (3) fan shaped (i.e., radiating along an arcfrom a point or small region), (4) multiple fan shaped (i.e., radiatingalong at least two arcs from a point or small region), (5) gridstructured, and (6) any other essentially two dimensional flow patternin the distribution layer, depending on the needs of the product. Theimportant point is that the distribution layer can be designed so thatliquid contacting a region on the distribution layer that is intendedfor the liquid's contact is distributed along a flow pattern byarrangement of the axes of the fiber forming the capillary system tolocations in the structure remote from the contact region and where theliquid can be stored. This means that there is a first region in thedistribution layer in which either the axes of the fibers aresubstantially aligned with one another or from which the axes of thefibers radiate away. In one preferred embodiment, there is a secondregion in the distribution layer where either the axes of the fibers aresubstantially aligned with one another along a different direction thanthe direction of the axes of the fibers in the-first region or fromwhich the axes of the fibers radiate away in an arc.

Preferably, the distribution layer provides a flow pattern distributingthe liquid to at least two distinct regions, and more preferably atleast three distinct regions, of absorbent core material.

Preferably, the distribution layer includes at least two sets, and morepreferably at least three sets, of fibers that are aligned in theimpingement region and that are not parallel to each other outside ofthe liquid impingement region. The distribution layer even morepreferably includes a plurality of sets of fibers that are aligned inthe impingement region, that are not parallel to each other outside ofthe impingement region and that distribute liquid from the impingementregion substantially uniformly to more remote regions of the absorbentcore.

Preferably, the distribution layer includes yarns produced from thespontaneously transporting or wettable fibers having a hydrophilicsurface. The yarns (tows) in the distribution layer range up to 100,000denier. The spacing of the yarns can vary from no spacing, that is alladjacent yarns are touching, to spacings up to three times the yarndiameter. The dpf's of the individual fibers may vary from 5 to 150.Preferably, the MPF_(B) of the fibers in the distribution layer exceeds0.005 cc/(den*hr).

The choice of the yarn for the distribution layer is influenced by thedesired separation distance between the top sheet and the flowresistance layer. Typically 3.0 millimeter separation is the maximumuniform spacing distance. However, in some cases it is desirable to haveessentially all of the fibers forming a single bundle. In this case theseparation distance between the top sheet and the flow resistance layeris essentially zero at some edge of the article but may be up to 10millimeters where the fiber bundle is between the top sheet and the flowresistance layer.

In a preferred embodiment all of the fibers in the distribution layerare located within an approximately one inch wide band along a majoraxis centerline of the absorbent article.

The weight of the distribution layer depends on the type of product. Forfeminine napkins, the weight should be between ¼ and 2 grams with thelength of the fibers being between 7 and 25 centimeters. For diapers,the weight of the distribution layer may be between ½ and 4 grams withthe length of the fibers being between 10 and 40 centimeters. For adultincontinent products, the weight of the distribution layer should bebetween 1 and 10 grams with the lengths of the fibers being between 10and 70 centimeters.

The distribution layer may include fibers of at least two lengths. Thisenables transport of the liquid to regions at different lengths from theimpingement region. The specific lengths of fibers in the distributionlayer and the distribution of those lengths depends on the design of theabsorbent article.

The flow resistance layer provides two primary functions. First, theflow resistance layer provides a resistance to flow that isperpendicular to the plane of the layer. This first function preventsthe liquid from reaching the core until after the liquid is distributed.Second, the flow resistance layer helps keep the directional capillariesin the distribution layer from contacting the core material where thatcontact is not desired. The flow resistance layer may have the samestructure and composition as the top sheet. The flow resistance layermay also be designed to have more flow resistance than the top sheet.The length of the flow resistance layer may be shorter-than thedistribution layer or the top sheet layer. This will allow thedistribution layer to transport liquid directly to predetermined regionsof the absorbent core beyond the edges of the flow resistance layer. Theflow resistance layer may also have a set of apertures through which thedistribution layer may communicate liquid to the absorbent core.Preferably, the set of apertures are spaced in a designed array. Forexample, the apertures could be arrayed to provide a substantiallyuniform liquid flux to all regions of the absorbent core.

Preferred Embodiments of the Invention

Spinnerettes, Fibers and Bundles

Referring now in more detail to the drawings, in which like referencenumerals indicate identical or corresponding parts throughout theseveral views, FIG. 1A is a schematic showing the dimensions of anaperture of a spinnerette used to make the fibers of example 1 includingarms 1, 2, 3, which radiate from a common axis 4. The arms 1, 2, 3, havea short dimension having a width W and a long dimension having a lengthof 150 W. The width w is 0.067 millimeters (which is 2.6 mils) wide.

FIG. 1B shows the details of a bore for an aperture of the spinneretteused in example 1 including a first (external) face 5A, a second(internal) face 5B, a thickness 6, and a blank bore 7. The thickness 6at the bottom of the blank bore 7 for the-spinnerette used in example 1is 50 mils (0.050 inches). The aperture is not shown in FIG. 1B.However, the spinnerette's apertures extend through the thickness 6between the bottom of the blank bore 7 and the first face 5A.

FIG. 1C shows a spinnerette 8 having a face 9 and bores with apertures10. There are 10 apertures in the spinnerette 8. The apertures arearranged along three rows and are all oriented the same way relative tothe rows.

FIG. 2 shows a cross-section of a fiber of example 1 in a photographtaken at a magnification of 156. The fiber's cross-section 11 is formedfrom polymer arms 1A, 2A, 3A, upon extrusion of the fiber from the arms1, 2, 3, of the aperture pattern shown in FIG. 1. The polymer arms 1A,2A, 3A, define channels 12, 13, and 14. Polymer arms 1A, 2A, and 3A,have distal tips 1B, 2B and 3B, respectively. The length of a linesegment that is tangent to two adjacent distal tips a channel, defines achannel width. For example, the distance between the distal tip 1B and2B defines the channel width 1C for the channel 12. Similarly, channelwidths 2C and 3C are the widths of the channels between the distal tips2B and 3B, and 3B and 1B, respectively.

FIG. 3A shows the dimensions of an aperture 20 in which W illustrates awidth of the aperture 20 and lengths of portions of the aperture areshown relative to the length W. The aperture 20 is formed from channelwalls 21, 22 which extend perpendicular to a channel base 23, andprotrusions 24 that extend away from the channel walls. The protrusions24 include an outer portion 25 that protrudes away from the channel andan inner portion 26 that protrudes into the channel. In addition,aperture 20 includes protrusion 27 which is an extension of the base 23beyond the intersection of the base 23 and the channel wall 21, andprotrusion 28 that is an extension of the channel wall 21 beyond theintersection of the channel wall 21 and the channel base 23. Protrusionssimilar to protrusions 27 and 28 exist near the intersection of channelwall 22 and channel base 23. The protrusions 25, 26, 27, 28 are shown asbeing five times as long as the width W. However, those protrusionscould be longer or shorter, depending upon the desired cross-section ofthe fiber produced therefrom. In addition, the protrusions 24 that arefurther from the intersection of the channel wall 21 and the base 23 maybe longer than the protrusions closer to the intersection of the channelwall 21 and the channel base 23 in order to increase the surface area ofthe channel in the polymer fiber resulting from the extrusion of polymerthrough the aperture 20. Similarly, the protrusions 24A along the base23 that are near the center of the base 23 may be longer than theprotrusions 24 from the base 23 that are nearer the channel walls 21,22, in order to increase the surface area of the channel of the polymerfiber resulting from extrusion of polymer through the aperture 20. Theprotrusions along the channel walls and base of the aperture 20 do notneed to be evenly spaced, and the relative lengths of the walls in thebase may vary from those shown in FIG. 3A. The width W is 0.090millimeters for the aperture 20. The base 23 extends 70 W, and the arms21, 22 extend about 47 W.

FIG. 3B shows a bore detail of a partial sectional view 30 for anaperture of a spinnerette used in example 2. The aperture is not shownin FIG. 3B. The partial sectional view 30 shows surface 31 and face 32spaced from one another by a dimension 33A which is 0.092 plus or minus0.02 inches in the spinnerette used in example 2. The aperture 20 of thespinnerette used in example 2 is machined through the blank dimension33A. The corresponding blank dimension in the other examples range fromabout 0.040 inch to 0.100 inch. Surface 31 along with surface 34partially define the bore 33. Bore 33 is also defined by a beveledsurface 35. The diameter of the bore 33 of the spinnerette used inexample 2 is about 0.36 inches. That is, the spacing between surfaces 34and 35 shown in FIG. 3B is about 0.36 inches for the spinnerette used inexample 2. Surface 35 is beveled at a 45° angle relative to surface 34.

FIG. 3C shows the spinnerette 41 used in example 2 having the bore andaperture pattern 40. The bore pattern consists of bores aligned in fiverows in which the apertures are all oriented the same way.

FIG. 4 is a photocopy of a photograph taken at 162 magnification offiber cross-sections including cross-section 45. Cross-section 45includes polymer arms 46A, 46B, and polymer base 46C. The polymer arms46A, 46B extend from the polymer base 46C such that the base and eacharm forms an angle of substantially greater than 90°. The cross-section45 includes protrusions 47 extending from the polymer arms 46A, 46B andthe polymer base 46C that correspond to the protrusions 24, 27, 28 ofthe aperture 20 of the spinnerette shown in FIG. 3. The cross-section 45has a channel width 46D.

The polymer arms 46A, 46B and the polymer base 46C form angles ofintersection substantially greater than the 90° angles of intersectionshown for the base 23 and the arms 21 and 22 of the aperture 20 of thespinnerette shown in FIG. 3A. The fiber's angles being greater than theaperture's angles is due to the effect of surface tension on the shapedmolten polymer extruded from the shaped aperture. The protrusions 47 ofthe cross-section 45 of the polymer fiber have an aspect ratio (i.e.,height to width ratio) substantially smaller than the aspect ratio ofthe protrusions 24, 27, 28 in the aperture 20 of the spinnerette shownin FIG. 3A also due to the effect of surface tension on molten polymerextruded through the aperture 20.

FIG. 5A shows a partial sectional view 50 of a bore detail for the boreand the aperture shown in FIG. 5B. The partial sectional view 50 issimilar to the partial sectional view shown in FIG. 1B and does not showthe aperture through the bottom of the bore.

FIG. 5B shows an aperture 51A in a bore 51B including long arms 52A and52C and short arms 52B and 52D. The arms 52A, 52B, 52C and 52D extendaway from a locating point defining 90° angles with one another.

FIG. 5C is a schematic diagram identifying relative dimensions of theaperture 51A of example 3. The long arms 52A, 52C have a length of 150 Wand the short arms 52B and 52D have a length of 75 W. 52A, 52B, 52C and52D all radiate from a common axis 52E. W is the width of the aperturein each arm perpendicular to the direction in which that arm extends.The width W is 0.067 millimeters (which is 2.6 mils).

FIG. 5D shows a spinnerette 53 having apertures 51A in the bores 51B forthe spinnerette face 54 of example 3. There are thirteen apertures 51Aaligned in three rows in the spinnerette 53.

FIG. 6 is a photocopy of a photograph taken at a magnification of 158showing a cross-section 60 of a polymer fiber of example 3. The polymercross-section 60 includes the long arms 61A, 61C, and the short arms61B, 61D. The arms 61A, 61B, 61C and 61D form channels 62A, 62B, 62C,and 62D, which have channel widths 63A, 63B, 63C, and 63D. Channels 62A,62B, 62C, and 62D are substantially similar to one another due to theirformation from the spinnerette having apertures that are each symmetric,as shown in FIG. 5D.

FIG. 7A shows a partial side sectional view of a bore 70 for an apertureof the spinnerette of example 4 shown in FIG. 7B. The aperture is notshown.

FIG. 7B shows the bore 70 and the aperture 71 of a spinnerette ofexample 4. FIG. 7B also shows the arms 72A, 72B, 72C, and 72D of theaperture 71. For the spinnerette used in example 4, the length 73 isabout 0.62 inches, the length 74 is about 0.50 inches, the length 75 isabout 0.065 inches, the length 77 is 0.80 inches, the length 76 is 0.93inches, and the length 78 is 0.065 inches. The arms 72A, 72B, 72C, and72D all extend from a common axis 72E as shown in FIG. 7C. Moreover, thearms 72A and 72C are co-linear, the arms 72B and 72D are co-linear, andthe arms 72B and 72D are perpendicular to the arms 72A and 72C.

FIG. 7C is a schematic illustrating dimensions of the aperture 71. FIG.7C shows the lengths of the arms 72A, 72B, 72C, and 72D as 183 W, 196 W,40 W, and 80 W, respectively. W represents the width of each of the armsof the aperture 71. The width W is 0.067 millimeters (which is 2.6 mils)in aperture 71.

FIG. 7D shows the spinnerette 80 having a pattern 79 of the bores 70 andthe apertures 71 of example 4. There are eleven apertures 71 and aspinnerette face 80, and the apertures 71 are aligned in three rows inthe spinnerette 80 to form the pattern 79.

FIG. 8 shows a photocopy of a photograph taken at a magnification of 158of a cross section 81 of a fiber of example 4 formed from thespinnerette shown in FIGS. 7A-7D. Cross-section 81 includes polymer arms82A, 82B, 82C, and 82D. The polymer arms 82A-82D have distal tips83A-83D, respectively. The polymer arms 82A-82D also define channels84A-84D, as shown. The length between the distal tips 83A and 83B definethe channel width 85A of the channel 84, which is also illustrated inFIG. 8. The channel width 85B is the length between the distal tips 83Band 83C. The channel width 85C is the length between the distal tips 83Cand 83D. The channel width 85D is the length between the distal tips 83Dand 83A. The fiber having the cross-section 81 shown in FIG. 8 is formedby extrusion from aperture of the spinnerette face 80 shown in FIG. 7D.The deviation of the angles between the polymer arms 82A-82D for thecross-section 81 from right angles is due to the extrusion process.

FIG. 9A shows a bore 90 in a partial sectional view of the spinneretteused in example 5.

FIG. 9B shows a plan view of the bore 90 and an aperture 91 of thespinnerette of example 5. The aperture 91 includes the arms 92A, 92B,and 92C.

FIG. 9C is a schematic identifying the relative dimensions of theaperture 91 of the spinnerette of example 5. FIG. 9C shows that the arms92A and 92C define an angle of 120°, and that the arm 92B defines anangle of 60° with each of the arms 92A and 92C. Moreover, FIG. 9C showsthat the arms 92A and 92C have lengths which are 100 times their widths,W, and that the arm 92S has a length that is 30 times its width, W. Thewidth W in aperture 91 is 0.064 millimeters.

FIG. 9D shows the spinnerette 95 used in example 5 having the face 96and including twenty bores 90 in a pattern of three rows. The twentyapertures 91 shown in FIG. 9D are aligned in three rows such thatlocating points for the apertures in each row define a line.

FIG. 10 is a photocopy of a photograph taken at a magnification of 163of a polymer cross-section 100 of a polymer fiber formed from thespinnerette 95 shown in FIGS. 9A-9D. The polymer cross-section 100includes arms 101A, 101B, and 101C. The arms 101A, 101B, 101C, havedistal tips 102A, 102B, and 102C, respectively. Arms 101A and 101Bdefine channel 103 and arms 101B and 101C define channel 104. The lengthbetween distal tip 102A and 102B defines the channel width 103A. Thelength between the distal tip 102B and 102C defines the channel width104A.

FIG. 11A is a partial sectional view showing the bore 110 for anaperture of the spinnerette 118 used in example 6.

FIG. 11B shows an aperture 111 in the bore 110 and having the arms 112A,112B, and 112C.

FIG. 11C is a schematic showing the dimension of aperture 111 of thespinnerette 118 used in example 6. FIG. 11C shows that the arms 112A,112B, 112C all radiate from a common axis 112D and radiate at anglesspaced by 120° from one another. FIG. 11C also shows that the arms 112A,112B, and 112C have lengths that are 150 times their width, W. The widthW is 0.067 millimeters in aperture 111.

FIG. 11D shows a spinnerette 118 used in example 6 having the bores 110and the apertures 111 in the aperture pattern 117. The apertures 111 inthe pattern 117 are aligned in three rows such that center points forapertures in each row define a line.

FIG. 12 is a photocopy of a photograph at a magnification of about 190of a polymer cross-section 120 of a fiber of example 6 formed using thespinnerette 118 shown in FIGS. 11A-11D. The polymer cross-section 120includes the arms 121A, 121B, and 121C, which all radiate from a centralpoint. The arms 121A, 121B, and 121C have distal tips 122A, 122B, and122C, respectively. The arms 121A and 121B define channel 123. The arms121B and 121C define the channel 124. Arms 121C and 121A define thechannel 125. The length between the distal tips 122A and 122B definesthe channel width 123A of channel 123. The length between the distaltips 122B and 122C defines the channel width 124B of the channel 124.The length between the distal tips 122C and 122A defines the channelwidth 125A of the channel 125. Channel 123 is defined by arms thatdefine an angle of less than 120°. The channel 124 is also defined byarms that define an angle of less than 120°. The channel 125 is definedby arms that is define an angle of greater than 120°.

FIG. 13A is a partial sectional view showing a bore 130 of thespinnerette 137 used in example 7.

FIG. 13B shows the bore 130 and an aperture 131 of the spinnerette 137used in example 7 having arms 132A, 132B, 132C, and 132D.

FIG. 13C is a schematic showing the dimensions of aperture 131 ofexample 7. FIG. 13C shows that the arms 132A and 132B have lengths thatare 105 times their width, W, and that the arms 132C and 132D havelengths that are 15 times their width, W. In addition, FIG. 13C showsthat arms 132A and 132B define an angle of 75° between them. The width Win aperture 131 is 0.084 millimeters. Arms 132A, 132B, 132C and 132D allradiate from a common axis 132E.

FIG. 13D shows a spinnerette aperture pattern 136 including tenapertures 131 in the spinnerette 137. The apertures 131 in thespinnerette 137 are aligned so that all of the apertures 131 have thesame orientation and form two rows of three apertures and one row offour apertures.

FIG. 14 is a photocopy of a photograph at a magnification of about 130of a polymer cross-section 140. The polymer cross-section 140 includesthe arms 141A, 141B, 141C, and 141D. The arms 141A, 141B, 141C, and 141Dhave distal tips 142A, 142B, 142C, and 142D, respectively. The arms 141Aand 141B are much longer than the arms 141C and 141D.

The arms 141A and 141B define a channel 143. The arms 141B and 141Cdefine a channel 144. The arms 141C and 141D define a channel 145. Thearms 141D and 141A define a channel 146. The width 143A of the channel143 is defined by the length between the distal tips 142A and 142B. Thewidth 144A of the channel 144 is defined by the length between thedistal tips 142B and 142C. The width 145A of channel 145 is defined asthe length between the distal tips 142C and 142D. The width 146A of thechannel 146 is defined as the length between the distal tips 142D and142A.

FIG. 15A is a partial sectional view of the spinnerette 158 used inexample 8 showing the bore 150.

FIG. 15B is a plan view showing an aperture 151 in the bore 150 andhaving the arms 152A, 152B, and 152C.

FIG. 15C is a schematic identifying the relative dimensions of theaperture 151 in the spinnerette 158 used in example 8. FIG. 15C showsthat the length of the arm 152A is 100 times its width, W, the length ofthe arm 152B is 160 times its width, W, and that the length of the arm152C is 100 times its width, W. In addition, FIG. 15C shows that thearms 152A and 152C each form an angle of 80° with the arm 152B. Thewidth W is 0.084 millimeters in the aperture 151. Arms 152A, 152B and152C all radiate from a common axis 152D.

FIG. 15D is a plan view showing the spinnerette 158 having thespinnerette aperture pattern 157 having ten apertures 151. All of theapertures 151 in the spinnerette aperture pattern 157 are oriented inthe same direction.

FIG. 16 is a photocopy of a photograph taken at a magnification of about230 of a polymer cross-section 160 of a fiber of example 8 formed usingthe spinnerette shown in FIGS. 15A-15D. The polymer cross-section 160includes the arms 161A, 161B, and 161C. The arms 161A, 161B, and 161Ceach have distal tips 162A, 162B, and 162C. The arms 161A and 161Bdefine the channel 163. The arms 161B and 161C define the channel 164.The arms 161C and 161A define the channel 165. The width 163A of thechannel 163 is defined by the length between the distal tips 162A and162B. The width 164A of the channel 164 is defined by the length betweenthe distal tips 162B and 162C. The width 165A of the channel 165 isdefined by the length between the distal tips 162C and 162A.

FIG. 17A is a partial sectional view of the spinnerette 181 used inexample 9 showing the bore 170. The dimension 171 is 0.050 inches andbevel 172 is 0.010 inches at 45° for the spinnerette 181 used in example9.

FIG. 17B is a plan view of the bore 170 and an aperture 173 of thespinnerette 181 used to make the fibers of example 9. The aperture 173in the bore 170 defines a curved section 174 and the protrusions 175.

FIG. 17C shows that the radius at the center of the curved section ofthe aperture 173 is about 138 times the width W of the curved section ofthe aperture. FIG. 17C shows that the distance from the center pointdefined by the curved section 173 to the distal tips 179 of theprotrusions 175 is about 143 times the width W of the curved section 174of the aperture 173. In addition, FIG. 17C also shows that theprotrusions 179 are spaced at 5° intervals from one another. The width Wis 0.067 millimeters in the aperture 173.

FIG. 17D is a plan view showing the spinnerette 181 used in example 9and the spinnerette aperture pattern 180. There are twelve bores 170 andapertures 173 in the aperture pattern 180. The twelve apertures arealigned along three rows. The center row is defined by six alignedapertures. The outer two rows are defined by three aligned apertures.

FIG. 18 is a photocopy of a photograph at a magnification of about 87 ofpolymer cross-sections including the polymer cross-section 185 formedusing the spinnerette shown in FIGS. 17A-17D. The polymer cross-section185 does not have a planar wall. However, the polymer section 185 has acenter section 186 with a first curvature, side sections 187 and 188having a second curvature that is greater than the first curvature, anddistal tips 189 and 190. Near the distal tips 189 and 190 are surfaces191 and 192 the tangents to which intersect the inner surface 193. Thesurfaces 191 and 192 oppose the inner surface 193. The inner surface 193is relatively smooth compared to the relatively rough outer surface 194.The roughness of the relatively rough surface 194 is due to the presenceof the protrusions 175 in the aperture 173 during the extrusion from thespinnerette 181 during the spinning of the fiber of example 9. Althoughthe surfaces 191 and 192 oppose the inner surface 193 in the fiber ofexample 9, that opposition is not necessary. That is, the outer ends ofthe polymer cross-section 185 may be oriented so that the surfaces 191and 192 near the distal tips 189 and 190 of the polymer cross-section donot oppose other portions of the cross-section. The polymercross-section 185 has a shape that looks like the letter “C”. Thesurface 191 is continuous with the inner surface 193, and the innersurface 193 is continuous with the surface 192. The surfaces 191, 192,and 193 define the channel 195. The channel width 195A of the channel195 is defined as the distance between the distal tips 189 and 190 ofthe polymer cross-section 185.

FIG. 19A shows the generalized version for the polymer cross-section 200of a fiber of prophetic example 10. FIG. 19A includes the first arminner section 201, the first arm outer section 202, the second arm innersection 203, and the second arm outer section 204. The length of thefirst arm inner section is shown as L₂, the length of the first armouter section shown as L₁, the length of the second arm inner section isshown as L₃, and the length of the second arm outer section is shown asL₄. FIG. 19A also shows that the width of each of the arm sections is W,that the angle defined by the inner arm sections 201, 203 is θ₂ that theangle defined by the first inner arm section 201 and the second innerarm section 202 is θ₁, and that the angle defined by the second innerarm section 203 and the second outer arm section 204 is θ₃. The armsections 201, 202, 203, and 204 define the channel 205. The width of thechannel 205 at its mouth is identified in FIG. 19A as X₁.

FIG. 19B is another schematic of a polymer cross-section 200A of a fiberof prophetic example 10 having different values for the parameters thanthe parameters shown for the cross-section 205 in FIG. 19A.

FIG. 19C shows a plan view of an aperture 206 of a spinnerette than canbe used to make the polymer cross-sections 200 and 200A.

Preferably, for prophetic example 10, θ₁, θ₂, and θ₃ are between 110°and 140°. Preferably, L₂/W is greater than or equal to 5. PreferablyL₃/W is greater than or equal to 5. Preferably L₁/W is less than orequal to 10. Preferably L₄/W is less than or equal to 10. Preferably thebulk factor of the polymer fiber having the cross-section 200 is greaterthan or equal to 4. Preferably the width W of the polymer cross-section200 is greater than or equal to 3 microns and is less than or equal to15 microns. Preferably, the adhesion tension of distilled water on thesurface of the polymer fiber having the cross-section 200 of propheticexample 10 is greater than 25 dynes per centimeter with distilled water.

More preferably, the angles θ₁, θ₂ and θ₃ are all about 120°. Morepreferably, X₁ is greater than or equal to 250 microns, and even morepreferably greater than 300 microns. More preferably, L₂ equals L₃ andL₁ equals L₄.

Preferably, θ₁ and θ₃ are each less than the quantity of 180° minus onehalf of θ₂. This relationship provides the outer arms 202 and 204 angledtowards one another such that the mouth of the channel 205 is narrowerthan the wide point of the cross-section. That narrowing at the mouth ofthe channel inhibits registration of adjacent fibers in which theinter-fiber capillaries are much less than the depth of the channel 205.

Moreover, each of the arm sections 201, 202, 203, and 204 may includeprotrusions having a width of about W and a length of protrusionextending no more than 3 W. Moreover, the ratio of L₂ to L₃ should bebetween 0.5 and 2.0. Moreover, the ratio between L₄ and L₁ should bebetween 0.5 and 2.0.

The foregoing relationships between the angles θ₁, θ₂, and θ₃, thelengths L₁, L₂, L₃, and L₄, and the width W, and the absolute values forthe lengths and widths identified above are believed to provide fibershaving novel large values for the maximum potential flux for bundles offibers.

FIG. 20 is a schematic showing the dimensions of the polymercross-section 210 of another prophetic example having the generalizedversion of the cross-section 60 shown in FIG. 6 for the fiber of example3. The polymer cross-section 210 includes the arms 211A, 211B, 211C, and211D. The arms 211A, 211B, 211C, and 211D, have the distal tips 212A,212B, 212C, and 212D. The arms 211A, 211B, 211C, 2111D define thechannels 213A, 213B, 213C, and 213D. The length of the arms 211A, 211B,211C, and 211D are illustrated in FIG. 20 as L₂, L₁, L₄ and L₃respectively. The channel width, which is defined as the width betweenthe distal tips of the walls defining the channel are illustrated inFIG. 20 as X₁ for the channel 213A, X₄ for the channel 213B, X₃ for thechannel 213C, and X₂ for the channel 213D. The width throughout thepolymer cross-section 210 is defined as W.

Preferably, for the cross-section 210, the angles θ₁, θ₂, θ₃, θ₄ are allapproximately 90°. Preferably, all four angles are between 70° and 110°.Preferably, the ratios of the lengths L to the width W is greater than 5for L₁, L₂, L₃, and L₄. Preferably, at least one of the ratios betweenthe lengths L₁ and L₄ to the width W is greater than 10. Preferably, thebulk factor of the fiber having the polymer cross-section 210 is greaterthan 4.0. Preferably, the width W is greater than 3 microns and lessthan or equal to 15 microns. Preferably, the adhesion tension withdistilled water on the surface of the fiber having the cross-section 210is greater than 25 dynes per centimeter. Preferably, the channel widthx₁ is greater than 250 microns, and more preferably greater than about300 microns. Preferably, the lengths L₂ equals the length L₃ and thelength L₁ equals the length L₄.

Preferably, for the cross-section 210, the angles θ₁ and θ₂ are lessthan the quantity defined by 180° minus one half of the angle θ₂. Thisrelationship between θ₁ and θ₂ inhibits registration, thereby preventingcapillaries that are too narrow.

In addition, each of the arms 211A, 211B, 211C, and 211D may have one ormore protrusions there along in which each of the protrusions has awidth of approximately W and is no more than about 3W long. In addition,the ratio of the length L₂ to the length L₃ and the ratio of the lengthL₄ to the length L₁ should be between about 0.5 and about 2.0.

FIG. 21A shows the generalized version of the fiber cross-section 220 ofprophetic example 11. Cross-section 220 includes the arms 221A, 221B,221C, and 221D, and base 222. The base 222, the arm 221A, and the arm221B define the channel 223. The base 222, the arm 221C, and the arm221D define the channel 224. FIG. 21A illustrates the length of the base222 as L₅, and the length of the arms 221A, 221B, 221C, and 221D, as L₃,L₁, L₂, L₄, respectively. FIG. 21A illustrates the angles between thebase 222 and the walls 221A , 221B, 221C, and 221D as θ₃, θ₁, θ₂, θ₄,respectively, and defines the width of the fiber as W.

Preferably, the angles θ₁, θ₂, θ₃, θ₄ are greater than or equal to 60°and less than or equal to 120°. Preferably, the ratios of the lengths ofeach of the walls, L₁, L₂, L₃, L₄ to the length of the base L₅ is lessthan or equal to 0.3. Preferably, the ratio of the lengths of each ofthe walls L₁, L₂, L₃, L₄ to the width W is greater than or equal to 5.Preferably, the length of the base L₅ to the width W is equal to orgreater than 10. Preferably, the width W is less than or equal to 15microns, more preferably less than 10 microns, and still more preferablyless than 5 microns, but wide enough to provide sufficient stiffness tothe fibers' cross-sections so that the fibers' cross-sections do notsubstantially deform and collapse the capillaries due to the capillaryforces pressing the fibers together. However, the thinnest structureswhich can be made using state of the art spinnerette technology andstate of the art extrusion processes have shown no evidence of any suchcollapse under capillary forces. The thinnest structures that can befabricated have widths W of about 3 microns. The thinner the width W theless polymer material is needed to provide the distribution function.The relationship of polymer material is represented in the MPF_(B)through the MPF_(B)'s dependence upon the specific volume.

Preferably, the adhesion tension of the surface of the fiber withdistilled water is equal to or greater than 25 dynes/cm.

More preferably, both of the channels' widths X₂ and X₁ are equal to orgreater than 250 microns, and more preferably are equal to or greaterthan 300 microns. More preferably, L₁, L₂, L₃, L₄ are all approximatelyequal. Preferably, each of the ratios L₁/L₂ and L₃/L₄ are equal to orgreater than 0.5 and less than or equal to 2.0. Each of the arms221A-221D may have protrusion of up to 3W long. Any such protrusionalong with each arm of the fiber should preferably fit within a 10W widepair of parallel lines delimiting the arm of the fiber, as shown in FIG.25.

FIG. 21B is a schematic plan view of the shape of a spinnerette aperture225 the use of which will result in a fiber having the cross-section226.

FIG. 21C shows the fiber cross-section 226 of the prophetic example 11.The curvature of the outer arms 227A, 227B, 227C, and 227D away from thebase 228 results from the surface tensions during the extrusion process.

FIG. 21D is a schematic plan view showing the shape of a spinneretteaperture 229 the use of which will result in a fiber having thecross-section 220 shown in FIG. 21A with the θ angles all being 90°.

FIG. 21E is a schematic plan view showing the shape of the spinneretteaperture 230 the use of which will result in a fiber having thecross-section 220 shown in FIG. 21A with the θ angles all being 90°.

FIG. 21F is a schematic plan view showing the shape of the spinneretteaperture 231 the use of which will result in a fiber having thecross-section 220 shown in FIG. 21A with the θ angles all being 90°.

FIG. 21G is a schematic plan view showing the shape of the spinneretteaperture 232 the use of which will result in a fiber having thecross-section 220 shown in FIG. 21A with the θ angles all being 90°.

FIG. 22A is a schematic of a cross-section 240 of a fiber showing thegeneralized version of the dimensions of cross-sections of the fibers ofexample 5. The cross-section 240 includes the arms 241A, 241B, and 241Cwhose lengths L₁, L₂, and L₃ are illustrated in FIG. 22A. The arms 241Aand 241C have distal ends which define the channel 242 having thechannel width X₁ illustrated in FIG. 22A. The arms 241A and 241 B definethe angle θ₁ and the arms 241B and 241C define the angle θ₂.

The fibers having the cross-sections 240 preferably have the angles θ₁plus θ₂ being greater than or equal to 90° and less than or equal to170°. Preferably, the ratio of each of the lengths L₁ and L₂ to thewidth W is equal to or greater than 5, and at least one of these tworatios is equal to or greater than 10. Preferably, at least one of theratios of L₃/L₁ and L₂/L₁ is equal to or greater than 5. Preferably, thebulk factor of the fiber is equal to or greater than 3.0. Preferably,the width W is less than or equal to 15 microns, more preferably lessthan 10 microns, and still more preferably less than 5 microns, and theadhesion tension is equal to or greater than 25 dynes/cm with distilledwater.

Additional distinguishing characteristics of fibers defined by thegeneralized cross-section 240 of FIG. 22A are that X₁ is greater thanabout 250 microns, and more preferably greater than about 300 microns,that the sum of θ₁ plus θ₂ is between 100° and 140°, that θ₁ is aboutequal to θ₂, and that the ratio of L₂/L₃, is between about 0.5 and 2.0.

Moreover, the fibers defined by the generalized cross-section in FIG.22A may have one or more protrusions along their length. Each suchprotrusion may be approximately W wide and no more than 3W long.Further, the arms having the protrusion should fit within a 10W widecorridor, as shown in FIG. 25.

FIG. 22B shows the prophetic fiber cross-section 243 which will resultfrom use of the spinnerette aperture 244 shown in FIG. 22C because ofthe effects of surface tension on the molten polymer.

FIG. 22C shows the spinnerette aperture 244.

FIG. 23 shows the generalized cross-section 250 of the fibercross-section of example 6.

The cross-section 250 shown in FIG. 23 includes the arms 251A, 251B, and251C. The arms 251A and 251B define the channel 252A. The arms 251B and251C define channel 252B. The arms 251C and 251A define the channel252C. The width of the channels 252A, 252B, and 252C, are illustrated asX₂, X₃, and X₁, respectively. The length of the arms 251A, 251B, and251C, are illustrated as L₂, L₃, L₁, respectively. The walls 251A and251B define the angle θ₂. The walls 251B and 251C define the angle θ₃.The walls 251C and 251A define the angle θ₁.

Preferred characteristics for the generalized cross-section 250 are thatthe angles θ₁, θ₂ and θ₃ are between 110° and 130°, that the ratios foreach of L₁, L₂, and L₃, to the width W are equal to or greater than 5,that at least one of the ratios of L₂ and L₃ to the width W is greaterthan 10, that the bulk factor is equal to or greater than 4, that thewidth W is less than or equal to 15 microns, more preferably less than10 microns, and still more preferably less than 5 microns, and that theadhesion tension of the surface of the fiber with distilled water isequal to or greater than 25 dynes per centimeter.

Additional distinguishing characteristics of the fibers defined by thegeneralized cross-section 250 in FIG. 23 are that X₁ is greater thanabout 250 microns, and more preferably greater than about 300 microns,that θ₁ and θ₂ and θ₃ are each approximately equal to 120°, and that theratio of L₂ and L₃ is greater than about ½ and less than about 2.

Moreover, the fibers defined by the generalized cross-section 250 inFIG. 23 may have one or more protrusions along their length. Each suchprotrusion may be approximately W wide and no more than 3 W long.Further, any such protrusions along the arms of the fiber should fitwithin a 10 W wide corridor along the length of each arm, as shown inFIG. 25.

FIG. 24 shows a generalized version 260 of the cross-section of thefibers of example 8. The cross-section 260 includes the walls 261A,261B, and 261C having the illustrated lengths L₂, L₃, and L₁,respectively. The walls 261A and 261B define the angle θ₂ The walls 261Band 261C define the angle θ₁. The walls 261C and 261A define the angleθ₃. The walls 261A and 261B define the channel 262A. The walls 261B and261C define the channel 262B.

For the generalized cross-section 260, preferably θ₁ and θ₂ are between80° and 100°, and more preferably between 85° and 100°. Preferably θ₃ isbetween about 170° and 200°. Preferably, the ratios of each of thelengths L₁, L₂, and L₃ to the width W are greater than or equal to 5,and more preferably at least one of these ratios is also greater than orequal to 10. Further, it is preferred that the bulk factor is greaterthan about 3.0, the width W is between about three and about 15 microns,and that the adhesion tension of the surface of the fibers withdistilled water is greater than about 25 dynes per centimeter.

Additional distinguishing characteristics of the fibers defined by thegeneralized cross-section 260 are that X₁ and X₂ are both greater thanabout 250 microns, and more preferably greater than about 300 microns,that the lengths L₁, L₂, and L₃ are equal to one another, that the ratioof the length L₁ to L₂ is between about one half and about two, that theratio of the length L₃ to L₂ is between about 0.02 and 10.

Moreover, the fibers defined by the generalized cross-section 260 mayhave one or more protrusions along their length. Each such protrusionmay be approximately W wide and no more than 3 W long. Further, the armshaving the protrusions should fit within a 10 W wide corridor, as shownin FIG. 25. FIG. 25 shows the generalized fiber cross-section 270 andthe low wide corridors 271A, 271B and 271C. The cross-section 270includes the arms 272A, 272B, and 272C. Further, the arms 272B and 272Chave protrusions 273. Each of the arms 270A, 272B, and 272C is delimitedby a 10 W wide corridor, where W is the width of each of the arms.

FIG. 25 shows each arm of a fiber including its protrusions fittingwithin a 10 W wide corridor as required by the criteria for thegeneralized cross-section discussed hereinabove. All three of the armsshown in FIG. 25 fit within the 10 W width criteria.

FIGS. 26A-B illustrate the definition of the single fiber bulk factor.

FIG. 26A shows the fiber cross-section 280 which is used to define theprocedure for determining the single fiber bulk factor. The single fiberbulk factor is defined as the cross-sectional area of the channelsdivided by the cross-sectional area of the fiber.

The fiber cross-section 280 has the width W and includes the arms 282A,282B, and 282C, which have the distal tips 283A, 283B, and 283C. Thearms 282A, 282B, and 282C define the cross-sectional channel areas 281A,281B, and 281C. The cross-sectional channel areas 281A, 281B, and 281Care defined by the straight line segments tangent to the distal tips ofthe arms and the surfaces of the arms.

A determination, in arbitrary units, of the cross-sectional area of thechannels provides an area of 225, and a determination of thecross-sectional area of the fiber in the cross-section 280 provides anarea of 60. Therefore, the single fiber bulk factor for thecross-section 280 is 225/60=3.8.

FIG. 26B shows the fiber cross-section 290 and the cross-sectional areaof the channel 291 in hashing. Determination, in arbitrary units, of thearea of the cross-section of the channels 291 and the area of thecross-section 290 of the fiber provides 225 and 44 in arbitrary units.Therefore, the single fiber bulk factor for FIG. 26B is 5.1.

FIG. 30A shows the dimensions of the aperture 320 of the spinnerette 330used in comparative example 12. The aperture 320 includes the arms 321A,321B, 321C, 321D, and the base 322. FIG. 30A illustrates the relativedimensions in which the arms 321A are fifty times the width W of theaperture and the base 322 is forty times the width W of the aperture.The width W is 0.100 millimeters in the aperture 320. The aperture wascut using a conventional YAG laser machining system. The machining ofthe apertures of the spinnerettes disclosed herein can be accomplishedusing conventional laser machining systems.

FIG. 30B schematically illustrates the spinnerette 330 used incomparative example 12 showing the placement of bores 323 spaced at22.5° from one another in a circular pattern in the spinnerette 330.

FIG. 31 shows magnified views of cross-sections 324 of fibers ofcomparative example 12.

FIG. 32A is a side sectional view of a bore 331 having a blank thickness331A that is 0.050 inch of the spinnerette 340 used in comparativeexample 13.

FIG. 32B shows an aperture 332 of the bore 331 of the spinnerette 340used in comparative example 13.

FIG. 32C is a magnified view of the aperture 332 showing the relativedimensions of the aperture 332. The aperture 332 has a width W, and thelengths 333, 334, 335, 336, 337, and 338 which are respectively 67 W,33.5 W, 134 W, 67 W, 38.5 W, and 77 W. The width W is 0.084 millimetersin the aperture 332.

FIG. 32D shows the spinnerette 340 including the arrangement of thebores 331. The thirty-seven bores 331 are arranged in seven rows.

FIG. 33 shows a cross-section 341 of a fiber of comparative example 13.The cross-section 341 includes the arms 342A, 342B, 342C, and 342D, andthe base 343. There are small projections 344 projecting from the centerof the base 343. There are projections 345 projecting away from the base344 and away from the surface of the walls. The cross-section 341 isgenerally “H” shaped and defines two channels.

FIG. 34 shows a cross-section 345 of a fiber of comparative example 14.The shape of the cross-section 345 of comparative example 14 is similarto the shape of the cross-section 341 of comparative example 13.

FIGS. 35-37C show cross sections used in defining the procedure fordetermining the capillary channel area for flow for a single fiber. Thecapillary channel area for flow is an approximation, based upon theforces on the liquid and the geometry of the fibers, of thecross-sectional area along which the liquid flows. Capillary channels onthe surfaces of fibers are those channels where capillary forces arelarge compared to gravity. Channel width dimensions less than about 250microns are required for capillary forces to be large compared togravity. There are basically two types of cross-sectional geometries ofchannels, which are substantially parallel walled channels andsubstantially “V” shaped channels.

For all channels that have a channel width at the mouth of the channelof less than 150 microns, a straight line is drawn that closes the mouthof the channel. The enclosed channel area is defined as the capillarychannel area for flow. FIGS. 35 and 37A illustrate capillary channelarea for flow for fibers the widths of the channels of which are lessthan 150 microns. FIGS. 36A-C, 37B, and 37C illustrate the capillarychannel area for flow for various shaped channels that are wider than150 microns. The general principles relating to FIGS. 35-37C can be usedto define a the capillary channel area for flow for any channel'scross-section. In general, all surfaces of the cross-section that definean angle of less than or equal to 120° and that can be closed by 150micron long line segments are closed, and the sum of the area of theclosed section is defined as the capillary channel area for flow.Exclusion of areas having surfaces that define an angle of greater than120° excludes shallow regions that do not define channels deep enough tosubstantially affect the transport of a liquid along the fiber.

FIG. 35 shows a cross-section 350 of a fiber that includes arms351A-351G and a base (unnumbered). The arms 351A-351G form channels352A-352E. The two arms defining each one of the channels 352A-352E areless than 150 microns apart from one another. The capillary channel areafor flow for the fiber having the cross-section 350 is indicated by thehashed regions of the channels 352A-352E. The capillary channel area forflow is the area bounded by the walls of the channels and a straightline segment connecting the distal tips of the walls of the channels.

FIG. 36A shows a cross-section 360 of a fiber having arms 361A-361F thatdefine channels 362A-362D. The widths of the channels 362A-362D aregreater than 150 microns. The hashed regions 363A and 363B define thecapillary channel area for flow of the channel 362A. The hashed regions364A and 364B define the capillary channel area for flow of the channel362B. The hashed regions 365A and 365B define the capillary channel areafor flow of the channel 362C. The hashed regions 366A and 366B definethe capillary channel area for flow of the channel 362D. The hashedregions in FIG. 36A indicating the capillary channel area for flow ineach of the channels are defined by a 150 micron long line segmentpositioned (1) so that the ends of the line segment contact the surfaceof the fiber and (2) so that the line segment is perpendicular to abisector of the angle between the arms and the base that define thechannel. The capillary channel areas for flow shown in FIG. 36A aredefined by the one hundred fifty micron long line segments and thesurface of the arm and the surface of the base.

FIG. 36B shows an arm section 367 of a cross-section of a fiber and anarm section 368 of the cross-section of the fiber. The arm sections 367and 368 form a right angle. FIG. 36B illustrates a bisector 369 of theright angle and a 150 micron long line segment 370. The 150 micron longline segment 370 is positioned in accordance with the procedure fordefining capillary channel area for flow so that the line segment isperpendicular to the bisector 369. The area 371 between the arm sections367, 368, and the line segment 370 is the capillary channel area forflow for the portion of the cross-section of the fiber shown in FIG.36B.

FIG. 36C shows a portion of a cross-section of a fiber which includes ashort arm section 372 the length of which is 50 microns and a long armsection 373 the length of which is greater than 150 microns. FIG. 36Cshows a 150 micron long line segment 374 one end of which is in contactwith the distal tip 375 of the short arm section 372 and the other endof which in contact with the long arm section 373 to define a capillarychannel area for flow 375. The line segment 374 is not perpendicular tothe bisector 376. When one section of the fiber defining a wall of achannel is so short that it would not contact a 150 micron line that isperpendicular to the bisector of the angle between the wall and the baseof the channel, the procedure for determining capillary channel area forflow places one end of the 150 micron long line segment at the distaltip of the short channel wall and the other end of the line segmentalong the opposing wall of the channel.

FIG. 37A shows a cross-section 380 of a fiber having “V” shaped channelsin which the walls of the channels define an angle less than 120° andthe widths at the mouths of the channels are less than 150 microns. Thecapillary channel areas for flow 381A-381G are each defined by the areabetween two opposing arms of the cross-section 380 that form walls of achannel and a line segment contacting the distal tips of the two arms.In each case, the line segment is less than 150 microns long.

FIG. 37B shows a cross-section 390 of a fiber forming a “V” shapedchannel and which includes arms 391A and 391B. The distal tips 392A and392B of the arms 391A and 391B are greater than 150 microns apart. FIG.37B shows the 150 micron long line segment 393 which is perpendicular tothe bisector 394 of the angle defined by the arms 391A and 391B. Theline segment is positioned so that its ends contact the walls of thechannel. The capillary channel area for flow 395 is defined by the 150micron long line segment 393 and the arms 391A and 391B.

FIG. 37C shows a cross-section 400 of a fiber forming a distorted “V”shape that includes the long arm 401 and the short arm 402. FIG. 37Cshows the bisector 403 of the angle defined by the arms 401 and 402. A150 micron long line segment perpendicular to the bisector 403 would nothave-ends contacting the short arm of 402 and the long arm 401. The 150micron long line segment 404 is positioned so that one of its endscontacts the distal tip 405 of the short arm 402 and the other endcontacts the long arm 401. The capillary channel area for flow 406 isdefined by the line segment 404, the short arm 402, and the portion ofthe long arm 401 that connects the short arm and the point of contact atsegment 404.

FIGS. 38A and 38B show cross-sections illustrating the procedure fordefining the single fiber bulk factor (bulk factor). The bulk factor isdefined by the sum of the cross-sectional areas of the voids divided bythe cross-sectional area of the fiber.

FIG. 38A shows a cross-section 410 of a fiber having arms 411A, 411B,and 411C. The arms 411A, 411B, and 411C have distal tips 412A, 412B, and412C. The area defined by straight line segments between the distal tips412A, 412B, and 412C and the arms 411A, 411B, and 411C defines the voidcross-sectional areas 413A, 413B, and 413C. For the cross-section shownin FIG. 38A, the bulk factor equals the sum of the void areas (413A plus413B plus 413C) divided by the area of the fiber's cross-section 410.

FIG. 38B shows a cross-section 420 including the arms 421A-421F and thebase 422. The arms 421A-421F have distal tips 423A-423F. The areadefined by a line that contacts the distal tips of two of the arms anddoes not contact any other portion of the cross-section 420 defines thevoid areas 424A-C, 424E, 424F. The bulk factor of the cross-section 420is the sum of the void areas (of 424A plus 424B plus 424C plus 424E plus424F) divided by the area of the cross-section 420 of the fiber. For thecross-section 420 shown in FIG. 38B, the bulkfactor=[(Void₁+Void₂+Void₃+Void₄+Void₅)/(Dark Area)] where the termsVoid₁, Void₂, Void₃, Void₄, and Void₅ are illustrated in FIG. 38B. Notethat the arm 421B shown in FIG. 38B does not define separate void areason either side of it because a line tangent to the distal tip 423B andtangent to the distal tip of either of the adjacent arms 423A or 423Cwould also contact additional regions of the cross-section 420.

FIG. 39 shows a metal or plastic harp 430 defined by rims 431A-431D. Afiber having a portion 432A on the front side of the harp and a portion432B on the back side of the harp is wrapped around the harp and knottedat the knot 433 at the top of the harp. Additional fibers (unnumbered)are wrapped around the harp as illustrated in FIG. 39. The length of theharp between the rims 431B and 431D is illustrated as 25 centimeters inFIG. 39. Instead of the single fiber 432A, 432B, one or more bundles offibers could be wrapped around the harp. The same vertical rise testprocedure applies to single fibers and bundles of fibers. The bundle offibers that is used is typically the total number of fibers in thestrand of yarn, as the yarn was produced. This may vary from 3 to 100 ormore.

The vertical rise test procedure involves taking individual fibers orstrands and tying multiple closed loops of the fibers or strands aroundthe metal/plastic harp 430 as shown in FIG. 39.

With the laboratory at approximately 70° F. (21.1° C.) and 65% relativehumidity, the harp is placed in a beaker containing Syltint® Red or RedTest Solution. The height up the harp to which the liquid moves abovethe liquid level in the beaker after 15 minutes is recorded to thenearest 0.1 cm. Sixteen strands or fibers are typically wound on theharp and the average height of the rise of the liquid for the sixteenstrands is determined.

Liquid Acquisition/Distribution Structures

FIGS. 40A-B, 41A-C, 43A-B, 44, and 47-50 show the liquidacquisition/distribution and absorbent product structures of theinvention.

FIG. 40A shows a liquid acquisition distribution structure 440 having atop layer 441, a liquid distribution structure 442, and a flowresistance layer 443.

FIG. 40B pictorially shows the distribution of the liquid 446 due to aliquid insult 444 insulting the absorbent product 445. The liquid 446 ofthe insult 444 traverses the top layer 441 and contacts the liquiddistribution structure 442. The liquid distribution structure 442distributes the liquid 446 parallel to the top layer 441, andcommunicates the liquid to the absorbent core 447 at a plurality ofdistinct locations 448A-448I via lower liquid resistance regions. Theabsorbent product 445 has the back layer 449.

FIG. 41A is a top view of a liquid acquisition/distribution structure450 of the present invention showing the insult 444 and the fibers 445A,445B, and 445C of the liquid distribution structure. The fibers 445A,445B, and 445C are aligned in the same direction in order to transportthe liquid from the insult 444 along the axis of the bundles of thefibers, as illustrated by the arrows in FIG. 41A.

FIG. 41B shows a liquid acquisition/distribution structure 460 in whichthe fibers 461A, 461B, and 461C fan out from the region 462 of theliquid insult 444 in order to distribute the liquid from the insult 444along the fanned out regions 463 and 464.

FIG. 41C shows the liquid acquisition/distribution structure 470 inwhich the fibers 471A, 471B, and 471C fan out from the region 472 wherethe liquid insult 444 occurs. The fibers of the liquidacquisition/distribution structure 470 extend radially in a circularpattern from the region 472 in order to distribute the liquid radiallyoutward in all directions.

FIG. 42A includes a graph showing fractions of the flow versus thelocation of the flow along the major axis of an absorbent product and aschematic of the acquisition/distribution structure illustrating thelocation of the insult in the top layer. FIG. 42A shows that thedistribution 480 of the liquid along the top layer is distributed closeto the location of the insult on the top sheet.

FIG. 42B includes a graph showing the uniform distribution of the liquidalong the major axis of the absorbent product through the liquid flowresistance layer (which is the third layer of the liquidacquisition,distribution structure). FIG. 42B shows that the liquidacquisition/distribution structure functions to spread out the initialliquid distribution 480 to the distribution 481.

FIG. 42C includes a graph showing the distribution of the liquid throughthe liquid resistance layer 443 along the major axis of the absorbentproduct for an alternative liquid acquisition/distribution structure490. The acquisition,distribution structure 490 includes a top layer441, a distribution layer 442, and an inhomogeneous liquid flowresistance layer 443. The inhomogeneous resistance layer 443 includesthe low resistance areas 443A and 443C, and the high resistance area443B. The high resistance area 443B provides more resistance to the flowof liquid across that area of the liquid resistance layer 443 than thelow resistance areas 443A and 443C. The presence of the high resistancearea 443 reduces the flow through the high resistance area 443 relativeto the low resistance areas 443A and 443C resulting in the depression483 of the distribution 482 in the region of the high resistance area443B.

FIG. 42D includes a graph showing the distribution of the liquid throughthe liquid flow resistance layer 443 versus the location along the majoraxis of the absorbent product for the alternative liquidacquisition,distribution structure 500. The liquidacquisition/distribution structure 500 includes the permeable areas 443Dand 443F and the impermeable area 443E. The impermeable area 443Eprevents any transmission of the liquid resulting in the zero fractionof flow through the high resistance layer 443 in the region of theimpermeable area 443E shown in the distribution area 484.

FIG. 43A shows an absorbent product 510 comprising the liquidacquisition/distribution structure 511, and the absorbent core 512. FIG.43A illustrates with arrow heads where the transmission of liquid fromthe liquid acquisition/distribution structure 511 to the absorbent core512 occurs. Along the periphery of the absorbent core 512 in the regions514, 515, the liquid is communicated directly to the absorbent core 512after having been diverted by the high resistance layer 517. Theresistance layer 517 substantially or completely prevents the liquidfrom going through the resistance layer 517.

FIG. 43B shows an absorbent product 520 including a liquid acquisitionrdistribution structure 521 and an absorbent core 522 in which the highresistance layer 523 of the liquid acquisition,distribution structure521 separates the absorbent core 522 from the liquid distribution layer524 throughout the absorbent product.

FIG. 44A shows a top plan view of an absorbent product 520 indicating aregion 521 in the absorbent product that contains the liquidacquisition/distribution structure 523 shown in FIG. 44B.

FIG. 44B shows the liquid acquisition/distribution structure 523including the top layer 524, the liquid distribution structure or layer525 and the liquid resistance layer 526.

The liquid distribution structure or layer 525 consists of a pluralityof aligned fibers spread out in the form of a layer. The width 527 ofthe distribution layer 525 depends upon the desired absorbent productand the intended insult. Typically, the width 527 of the distributionlayer 525 in the region where the insult is intended will be at least aswide as the intended insult, which is typically between about 2 and 10centimeters.

FIG. 45A is a photocopy of a photograph of a magnified cross-section ofthe bundle 530 of the fibers used in the distribution structure inexample 15. Those fibers have round cross-sections. These fibers are notthe preferred fibers.

FIG. 45B shows a distribution of the cross-sections of fibers used inthe distribution structure in example 18.

FIG. 45C shows the cross-section of a bundle of the fibers used in thedistribution structure in example 20.

FIG. 45D shows the cross-section of a bundle of the fibers used in thedistribution structure in example 19.

FIG. 46A shows a cross-section of a bundle of the fibers used in thedistribution structure in example 21.

FIG. 46B shows a cross-section of a bundle of the fibers used in thedistribution structure in example 22.

FIG. 47A shows a top plan view of an acquisition/distribution structureurged in example 28 which includes the region 530 included in thedistribution layer. The region 530 has a width 531 of 2 centimeters anda length 532 of 16 centimeters. Further, dashed lines 533 and 534indicate the length of a 4 centimeter wide insult region 535.

FIG. 47B shows a section of the acquisition/distribution structure 540used in example 28 including the distribution of fiber bundle layer 535,a top layer 536, and a liquid resistance layer 537. The liquidresistance layer 537 includes a liquid impermeable section 538. In theliquid acquisition/distribution 540 used in example 28, the top layer536 and bottom layer 537 are formed from Dri-weave® (a perforatedpolyethylene film) and the impermeable section 538 is formed from aliquid impermeable polymer film.

FIG. 48 is a schematic side section view of an alternative absorbentproduct of the invention showing a liquid insult 550, a top sheet 551directly above a liquid acquisition/distribution structure 552, and theabsorbent cores 553 and 554. Adjacent to liquid acquisition/distributionstructure 552 and on either side thereof are absorbent cores 553 and554. The liquid acquisition/distribution structure extends to regions555 and 556 that are beneath the absorbent cores. Liquid resistancelayers 557 and 558 at least partially between the absorbent cores andthe liquid distribution layers sections 555 and 556 allow the liquid inthe distribution layer 552 to spread out so that the liquid impinges theabsorbent core along a substantial length of the bottom surfaces 559 and560 of the absorbent cores. Portions of the distribution layer may bebetween the flow resistance layer and the absorbent core in order toimprove the distribution of the liquid. Thus, the distribution layer maybe split into two layers, and each of the two layers extends under adifferent one of the two absorbent cores.

The distribution layer may be formed from a helically crimpedspontaneously wettable fiber tow or the bundled tows described hereinthat are divided into two sections on each end of the distributionstructure. These two sections are separated by the liquid resistancelayers 557, 558, which may be formed form thin plastic film. Thisseparation of parts of the distribution layer by the liquid resistancelayers 557, 558 allows part of the liquid to be transferred from theinsult region to the absorbent material close to the insult region(fibers on top of the liquid resistance layers 557, 558) and part of itto be transferred to the extremity of the pad (carried by the fibers onthe bottom of the liquid resistance layers 557, 558). The resistancelayers 557 and 558 could also be made from the same material as that ofthe top layer (e.g. Dri-weave®) and could extend the full length of theabsorbent cores 553 and 554.

The structure of FIG. 48 may be used in any absorbent article.Obviously, the size of the pieces required depends on the article ofchoice (i.e. feminine napkin or diaper, etc.). The specific volume ofthe spontaneously wettable tow in the insult region should be between 5and 75 cc/gm. The absorbent core storage material is fluff pulp althoughblends of fluff and SAP or chemically treated cellulose may also beused.

FIG. 49 shows another alternative embodiment of the absorbent product ofthe present invention in which there are three flow resistance layersbelow each of the absorbent cores. The liquid resistance layers 557A,557B, and 557C extend various lengths beneath the absorbent core inorder to more uniformly distribute the liquid to the bottom surface 559of the absorbent core 553. Further, the bottom liquid resistance layer557C may be liquid impermeable in order to prevent liquid from escapingfrom the absorbent product. Significantly, the distribution structure ofthe absorbent product shown in FIG. 49 splits into three separate layersseparated by the layered liquid resistance layers beneath each absorbentcore in order to provide uniform distribution of the liquid to thebottom surface of each absorbent core.

FIG. 50 shows still another alternative liquid acquisition/distributionstructure 560 which includes an insult region 561, and a distributionstructure that distributes the liquid away from the insult region 561.The liquid acquisition distribution structure 560 includes the tows,562, 563, 564 that have different lengths. The tows 562 extend from theinsult region 561 to points directly above the liquid flow resistancelayers 565, 566. The tows 564 extend substantially only the length ofthe insult region 561. The tows 563 extend underneath the liquid flowresistance layers 561 and 565, and extend beyond the ends of thoselayers. The different length tows are useful in distributing liquid todifferent distances away from the insult region 561 in order to make thedistribution of the liquid to the absorbent core (not shown in FIG. 50)more uniform. Variations may be made by using pieces of thin film thatare curved instead of straight. The curvature of the films can controlaccess to various locations in the absorbent core material.

In still another variation, there are three tows in the distributionstructure and the central tow may be about three times the size of theother two tows. The larger central tow provides a raised portion in thestructure which provides a better anatomical fit when the structure isused in a feminine napkin.

FIG. 51A is a schematic top plan view of an absorbent article ofprophetic example 29 showing the absorbent article 570's top layer 571and indicating the location of the distribution layer 572, the locationof the aperture or low resistance regions 573, 574, and 575 of theresistance layer 577 (see FIG. 51B), and including the arrows 576illustrating an intended liquid flow pattern from the region of the toplayer 571 above the aperture 574.

FIG. 51B is a partial side sectional view of the absorbent article 570showing the absorbent core 578 below the resistance layer 577. Theapertures 573 and 575 are larger than the aperture 574. The absorbentarticle is designed to receive a liquid insult above the aperture 574,and to evenly distribute the liquid to the core through the threeapertures 573, 574, and 575. Additional apertures may be provided in theresistance layer 577 in order to provide a more uniform distribution ofliquid to the absorbent core 578.

EXAMPLES 1-14

Fibers, Bundles and Spinnerettes

EXAMPLE 1

(110/125/125 Y, PET, Egan)

Example 1 describes the production of an undrawn continuous filamentyarn useful in bundle structures for enhanced transport of liquids. Theyarn is composed of 10 individual fibers, each having a Y-shapedcross-section with three equal arms and included angles of 110°, 125°,and 125°. The resulting fiber has three channels, two of which areapproximately equal in width and area, with the third channel beingslightly less in width and area.

Poly(ethylene terephthalate), (PET), polymer having an inherentviscosity (IV) of 0.75 and containing 0.2 percent titanium dioxide(TiO2) was used in preparing this yarn. Throughout the specification allIV values are measured in a 60/40 parts by weight solution ofphenol/tetrachloroethane at 25° C. and at a concentration of about 0.5gram of polymer in 100 mL of the solvent. The polymer was dried to amoisture level of less than or equal to 0.005 weight percent in aPatterson Conaform dryer at 120° C. for a period of at least 8 hours.The polymer was extruded at 280° C. using an Egan extruder having a 1.5inch (38.1 millimeter) diameter screw of length to diameter ratio of28:1. The polymer was spun through a spinnerette, numbered as I-1195,containing 10 individual orifices. The details of each orifice and thegeneral layout of the spinnerette holes are shown in FIGS. 1A-1C.

The fiber, which had an IV of 0.69, was spun in a spinning cabinethaving a cross flow air quench system using room temperature air at avelocity of about 51.8 meters/min. The individual fibers averaged 123dpf. The yarn was taken up on a Leesona winder at 1000 meters perminute.

Spinning lubricant LK-5598-E10 was applied to the fiber at a level of0.77 percent using a ceramic kiss roll just below the cabinet exit.LK-5598-E10 is a 10 weight percent solids water dispersion of thefollowing components: 10 weight percent solution ofpoly[polyethyleneglycol (1400) terephthalate], 44.1 weight percentsolids polyethylene glycol (400) monolaurate (oxyethylene fatty acidester), 44.1 weight percent solids polyethylene glycol (600) monolaurate(oxyethylene fatty acid ester), and 1.8 weight percent solids 4-cetyl,4-ethyl morpholinium ethosulfate (alkyl quaternary ammonium salt ofinorganic ester).

A typical fiber cross-section for a fiber of example 1 is shown in FIG.2. The generalized version is of the shape of the cross-section is shownin FIG. 23. The fiber's cross-section properties were measured usingfiber photomicrographs and a standard image analysis procedure. Liquidmovement properties of fiber bundles and single fibers were measuredusing a special fiber wetting instrument shown in FIG. 27. Thisinstrument is equipped with a video camera system capable of trackingthe advancing liquid/air interface and determining the initial wettingvelocity. Yarn specific volume was measured using a test methoddescribed earlier. Single Fiber Bulk Factor was calculated according tothe method described above. The 8-fiber bundle maximum potential fluxMPF₈ is calculated according to methods described in conjunction withFIG. 27. Single fiber Specific Capillary Volume (SCV), SpecificCapillary Surface Area (SCSA) and slenderness ratio are calculatedaccording to methods described in U.S. Pat. No. 5,200,248. Single fibermaximum potential flux MPF_(SF) is calculated according to methodsdescribed in connection with FIG. 27. Average denier per filament wasdetermined from the laboratory fiber cross-sectional area and thepolymer density. The “X Factor” is calculated according to the methoddescribed in U.S. Pat. No. 5,268,229.

Fiber and liquid movement properties are as follows:

X-Factor 1.21 dimensionless Denier per filament 123 dpf Channel width(avg.), 332 microns channel 1 (x₁, FIG. 2) Channel width (avg.), 537microns channel 2 (x₂, FIG. 2) Specific volume @ 0.05 5.58 cc/gmgram/denier tension Single fiber area 10,311 microns² Single fiber total80,770 microns² channel area Single fiber channel 10,492 microns² areafor flow Single fiber percent 0 percent channels <300 micron widthSingle fiber bulk factor 7.83 dimensionless Single fiber total perimeter1811 microns Single fiber specific 3.21 cc/gm capillary volume Singlefiber specific 577 cm²/gm capillary surface area Single fiberslenderness 25.3 dimensionless ratio Specific liq. movement force 0.0458dyne/den Single fiber initial 34.1 mm/sec liquid velocity 8-fiber bundleinitial 70.0 mm/sec liquid velocity 8-fiber bundle maximum 0.2701cc/(den*hr) potential flux Single fiber maximum 0.0210 cc/(den*hr)potential flux Single fiber vertical rise 3.65 cm after 15 min Bundlevertical rise after 6.04 cm 15 min MPF_(B)/MPF_(SF) 12.8 dimensionlessVR_(B)/VR_(SF) 1.66 dimensionless

FIG. 23 shows a generalized version of the fiber cross-sections.

EXAMPLE 2

(Knobby U, PET HX)

This example describes the production of an undrawn continuous filamentyarn not very useful in bundle structures for enhanced transport ofliquids. The yarn is composed of 22 individual fibers, each having a“knobby” rectangular U-shaped cross-section. The base of the rectangularU is longer than the two equal arms forming the sides of the U, and thearms extend from the base at included angles generally greater than 90°.The fiber has a single large channel.

Poly(ethylene terephthalate), (PET), polymer having an IV of 0.70 andcontaining 0.2 percent titanium dioxide (TiO₂) was used in preparingthis yarn. The polymer was dried to the same moisture level using thesame equipment as in example 1. The polymer was extruded at 270° C.through a Hills R & D Extruder (designated HX) having a one inch (25.4millimeter) diameter screw of length to diameter ratio of 24:1. Thepolymer was spun through a spinnerette, numbered I-1111, containing 22individual orifices. The details of each orifice and the general layoutof the spinnerette holes are shown in FIGS. 3A-3C.

The fiber, which had and IV of 0.63, was spun in a spinning cabinethaving a cross flow air quench system using room temperature air at avelocity of 12.8 meters/min. Spinning lubricant LK-5598-E10, the same asin example 1, was applied to the fiber at a level of 0.63 percent usinga ceramic kiss roll just below the cabinet exit. The individual fiberswere 96 dpf. The yarn was taken up on a Leesona winder at 1000 metersper minute. A typical fiber cross-section is shown in FIG. 4. Fibercross-section properties and liquid movement properties for singlefibers and 8-fiber fiber bundles were measured using the same methods asdescribed in example 1.

Fiber and liquid movement properties are as follows:

X-Factor 1.52 dimensionless Denier per filament 96 dpf Channel width(avg.), 365 microns channel 1 (x₁, FIG. 4) Specific volume @ 0.05 2.70cc/gm gram/denier tension Single fiber fiber area 8,046 microns² Singlefiber total 24,352 microns² channel area Single fiber MPF effective9,140 microns² channel area Single fiber percent 0 percent channels <300micron width Single fiber bulk factor 3.03 dimensionless Single fibertotal perimeter 1379 microns Single fiber specific 0.60 cc/gm capillaryvolume Single fiber specific 878 cm²/gm capillary surface area Singlefiber slenderness 85.7 dimensionless ratio Specific liq. movement force0.0447 dyne/den Single fiber initial liquid 22.3 mm/sec velocity 8-fiberbundle initial 54.0 mm/sec liquid velocity 8-fiber bundle maximum 0.0839cc/(den*hr) potential flux Single fiber maximum 0.0154 cc/(den*hr)potential flux MPF_(B)/MPF_(SF) 5.46 dimensionless Single fiber vertical2.58 cm rise after 15 min Bundle vertical rise 12.9 cm after 15 minVR_(B)/VR_(SF) 4.98 dimensionless

This bundle is not a good liquid mover.

EXAMPLE 3

(Plus, PET, Egan)

This example describes the production of an undrawn continuous filamentyarn useful in bundle structures for enhanced transport of liquids. Theyarn is composed of 13 individual fibers, each having a plus-shapedcross-section consisting of two opposing pairs of arms that form four90° included angles. Each opposing pair of arms is of equal length, butthe two pairs are of different length. The average width and area of thefour resulting channels are approximately equal.

Poly(ethylene terephthalate), (PET), polymer having an IV of 0.76 andcontaining 0.2 percent titanium dioxide (Tio₂) was used in preparingthis yarn. The polymer was dried to the same moisture level using thesame equipment as in example 1. The polymer was extruded at 280° C.using the same extruder as in example 1. The polymer was spun through aspinnerette, numbered I-1199, containing 13 individual orifices. Thedetails of each orifice and the general layout of the spinnerette holesare shown in FIGS. 5A-5D.

The fiber, which had an IV of 0.68, was spun in the same spinningcabinet as in example 1. The cross flow quench velocity was 36.6meters/min. Spinning lubricant LK-5598-E10, the same as in example 1,was applied to the fiber at a level of 0.99 percent using the sameequipment as in example 1. The individual fibers averaged 138 dpf. Theyarn was taken up on a Leesona winder at 500 meters per minute.

A typical fiber cross-section is shown in FIG. 6. The general version ofthis shape is shown in FIG. 20. Fiber cross-section properties andliquid movement properties for single fibers and 8-fiber fiber bundleswere measured using the same methods as described in example 1.

Fiber and liquid movement properties are as follows:

X-Factor 1.26 dimensionless Denier per fiber 38 dpf Channel width(avg.), 333 microns channel 1 (x₁, FIG. 6) Specific volume @ 0.05 4.28cc/gm gram/denier tension Single fiber fiber area 11,570 microns² Singlefiber total 77,083 microns² channel area Single fiber capillary 22,156microns² channel area for flow Single fiber percent 0 percent channels<300 micron width Single fiber bulk factor 6.66 dimensionless Singlefiber total perimeter 1953 microns Single fiber specific 2.77 cc/gmcapillary volume Single fiber specific 1121 cm²/gm capillary surfacearea Single fiber slenderness 19.0 dimensionless ratio Specific liq.movement force 0.0441 dyne/den Single fiber initial 42.7 mm/sec liquidvelocity 8-fiber bundle initial 68.9 mm/sec liquid velocity 8-fiberbundle maximum 0.1942 cc/(den*hr) potential flux Single fiber maximum0.0607 cc/(den*hr) potential flux MPF_(B)/MPF_(SF) 3.20 dimensionlessSingle fiber vertical 5.85 cm rise after 15 min Bundle vertical riseafter 7.88 cm 15 min VR_(B)/VR_(SF) 1.35 dimensionless

FIG. 20 shows a generalized version of this cross-section.

EXAMPLE 4

(Skewed Plus, PET, Egan)

This example describes the production of an undrawn continuous filamentyarn useful in bundle structures for enhanced transport of liquids. Theyarn is composed of 11 individual fibers, each having a skewedplus-shaped cross-section consisting of four arms of generally unequallength that meet to form four approximately 90° included angles. Thisresults in four channels having generally unequal widths and unequalareas.

Poly(ethylene terephthalate), (PET), polymer having an IV of 0.76 andcontaining 0.2 percent Titanium dioxide (TiO₂) was used in preparingthis yarn. The polymer was extruded at 280° C. using the same extruderas in example 1. The polymer was spun through a spinnerette, numberedI-1198, containing 11 individual orifices. The details of each orificeand the general layout of the spinnerette holes are shown in FIGS.7A-7D.

The fiber, which had an IV of 0.67, was spun in the same spinningcabinet as example 1. The cross flow quench velocity was 21.3meters/min. Spinning lubricant LK-5598-E10, the same as in example 1,was applied to the fiber at a level of 0.80 percent using the sameequipment as in example 1, The individual fibers averaged 123 dpf. Theyarn was taken up on a Leesona winder at 700 meters per minute.

A typical fiber cross-section is shown in FIG. 8. The general shape isshown FIG. 20. Fiber cross-section properties and liquid movementproperties for single fibers and 8-fiber fiber bundles were measuredusing the same methods as described in example 1.

Fiber and liquid movement properties are as follows:

X-Factor 1.22 dimensionless Denier per filament 123 dpf Channel width(avg.), 358 microns channel 1 (x₁, FIG. 8) Channel width (avg.), 125microns channel 2 (x₂, FIG. 8) Channel width (avg.), 347 microns channel3 (x₃, FIG. 8) Channel width (avg.), 624 microns channel 4 (x₄, FIG. 8)Specific volume @ 0.05 4.83 cc/gm gram/denier tension Single fiber fiberarea 10,313 microns² Single fiber total 63,911 microns² channel areaSingle fiber capillary 14,890 microns² channel area for flow Singlefiber percent 25 percent channels <300 micron width Single fiber bulkfactor 6.20 dimensionless Single fiber total perimeter 1897 micronsSingle fiber specific 2.21 cc/gm capillary volume Single fiber specific726 cm²/gm capillary surface area Single fiber slenderness 18.8dimensionless ratio Specific liq. movement force 0.0480 dyne/den Singlefiber initial liquid 38.2 mm/sec velocity 8-fiber bundle initial 73.0mm/sec liquid velocity 8-fiber bundle maximum 0.2378 cc/(den*hr)potential flux Single fiber maximum 0.0334 cc/(den*hr) potential fluxMPF_(B)/MPF_(SF) 7.12 dimensionless Single fiber vertical 4.51 cm riseafter 15 min Bundle vertical rise 8.91 cm after 15 min VR_(B)\VR_(SF)1.98 dimensionless

EXAMPLE 5

(Orig. Wing, PP, Egan)

This example describes the production of an undrawn continuous filamentyarn useful in bundle structures for enhanced transport of liquids. Theyarn is composed of 20 individual fibers, each having a wing-shapedcross-section formed by two arms of equal length. The smaller includedangle between these arms is bisected by a third shorter arm that resultsin two channels of approximately equal size and area.

Polypropylene, (PP), polymer having melt flow rate (MFR) of 18 grams ofpolymer per 10 minutes was used in preparing this yarn. MFRdetermination is per ASTM Test Method D-1238 at 230° C. using a diediameter of 2.095 mm and length of 8 mm. The polymer was spun through aspinnerette, numbered I-1187, containing 20 individual orifices. Thedetails of each orifice and the general layout of the spinnerette holesare shown in FIGS. 9A-9D.

The fiber was spun in the same spinning cabinet as example 1. The crossflow quench velocity was about 5.8 meters/min. Spinning lubricantLK-5598-E10, the same as in example 1, was applied to the fiber at alevel of 1.89 percent using the same equipment as in example 1. Theindividual fibers averaged 90.3 dpf. The yarn was taken up on a Leesonawinder at 250 meters per minute.

A typical fiber cross-section is shown in FIG. 10. The general shapesare shown in FIGS. 22A, 22B, and 24. Fiber cross-section properties andliquid movement properties for single fibers and 8-fiber fiber bundleswere measured using the same methods as described in example 1.

Fiber and liquid movement properties are as follows:

X-Factor 1.23 dimensionless Denier per filament 90.3 dpf Channel width(avg.), 387 microns channel 1 (x₁, FIG. 10) Specific volume @ 0.05 4.20cc/gm gram/denier tension Single fiber fiber area 11,028 microns² Singlefiber total 45,316 microns² channel area Single fiber capillary 10,195microns² channel area for flow Single fiber percent 0 percent channels<300 micron width Single fiber bulk factor 5.11 dimensionless Singlefiber total perimeter 2086 microns Single fiber specific 2.15 cc/gmcapillary volume Single fiber specific 1269 cm²/gm capillary surfacearea Single fiber slenderness 49.1 dimensionless ratio Specific liq.movement force 0.0716 dyne/den Single fiber initial 23.9 mm/sec liquidvelocity 8-fiber bundle initial 56.5 mm/sec liquid velocity 8-fiberbundle maximum 0.1407 cc/(den*hr) potential flux Single fiber maximum0.0194 cc/(den*hr) potential flux MPF_(B)/MPF_(SF) 7.25 dimensionlessSingle fiber vertical 0.83 cm rise after 15 min Bundle vertical riseafter 9.74 cm 15 min VR_(B)VR_(SF) 11.7 dimensionless

FIG. 22 shows a generalized version of this fiber cross-section.

EXAMPLE 6

(Balanced Y, PET, Egan)

This example describes the production of an undrawn continuous fiberyarn useful in bundle structures for enhanced transport of liquids. Theyarn is composed of 10 individual fibers, each having a generallysymmetric Y-shaped cross-section consisting of three arms havinggenerally the same average equal length that meet to form threeapproximately equal 120° included angles. This results in three channelshaving generally equal widths and equal areas.

Poly(ethylene terephthalate), (PET), polymer having an IV of 0.77 andcontaining 0.2 percent Titanium dioxide (TiO₂) was used in preparingthis yarn. The polymer was dried to the same moisture level using thesame extruder as in example 1. The polymer was spun through aspinnerette, numbered I-1208, containing 10 individual orifices. Thedetails of each orifice and the general layout of the spinnerette holesare shown in FIGS. 11A-11D.

The fiber, which had an IV of 0.75, was spun in the same spinningcabinet as in example 1. The cross flow quench velocity was about 16.8meters/min. Spinning lubricant LK-5598-E10, the same as in example 1,was applied to the fiber at a level of 0.36 percent using the sameequipment as in example 1. The individual fibers averaged 77 dpf. Theyarn was taken up on a Leesona winder at 1000 meters per minute.

A typical fiber cross-section is shown in FIG. 12. Fiber cross-sectionproperties and liquid movement properties for single fibers and 8-fiberfiber bundles were measured using the same methods as described inexample 1.

Fiber and liquid movement properties are as follows:

X-Factor 1.09 dimensionless Denier per fiber 77 dpf Channel width(avg.), 390 microns channel 1 (x₁ FIG. 12) Specific volume @ 0.05 7.22cc/gm gram/denier tension single fiber fiber area 6,464 microns² Singlefiber total 63,657 microns² channel area Single fiber capillary 9490microns² channel area for flow Single fiber percent 0 percent channels<300 micron width Single fiber bulk factor 5.11 dimensionless Singlefiber total perimeter 1519 microns Single fiber specific 1.64 cc/gmcapillary volume Single fiber specific 980 cm²/gm capillary surface areaSpecific liq. movement force 0.0613 dyne/den Single fiber initial 27.6mm/sec liquid velocity 8-fiber bundle initial 69.7 mm/sec liquidvelocity 8-fiber bundle maximum 0.3603 cc/(den*hr) potential flux Singlefiber maximum 0.0246 cc/(den*hr) potential flux MPF_(B)/MPF_(SF) 14.7dimensionless Single fiber vertical rise 2.85 cm after 15 min Bundlevertical rise 6.64 cm after 15 min VR_(B)/VR_(SF) 2.33 dimensionless

FIG. 23 shows a generalized version of the fiber cross-section.

EXAMPLE 7

(Crossed V, PET, Egan)

This example describes the production of an undrawn continuous fiberyarn useful in bundle structures for enhanced transport of liquids. Theyarn is composed of 10 individual fibers, each having a V-shapedcross-section consisting of two long arms of generally equal length thatcross to form one large dominant channel, two additional moderatelylarge channels of generally equal area and width that are adjacent tothe large dominant channel, and one small channel opposite the largedominant channel. The included angles of the large dominant channel andsmallest channel are approximately equal and the included angles of thetwo channels adjacent to the largest channel are approximately equal.

Poly(ethylene terephthalate), (PET), polymer having an IV of 0.77 andcontaining 0.2 percent Titanium dioxide (TiO₂) was used in preparingthis yarn. The polymer was dried to the same moisture level using thesame equipment as in example 1. The polymer was extruded at 281° C.using the same extruder as in example 1. The polymer was spun through aspinnerette, numbered I-1206, containing 10 individual orifices. Thedetails of each orifice and the general layout of the spinnerette holesare shown in FIGS. 13A-13D.

The fiber, which had an IV of 0.75, was spun in the same spinningcabinet as in example 1. The cross flow quench velocity was about 16.8meters/min. Spinning lubricant LK-5598-E10, the same as in example 1,was applied to the fiber at a level of 0.76 percent using the sameequipment as in example 1. The individual fibers averaged 169 dpf. Theyarn was taken up on a Leesona winder at 450 meters per minute.

A typical fiber cross-section is shown in FIG. 14. Fiber cross-sectionproperties and liquid movement properties for single fibers and 8-fiberfiber bundles were measured using the same methods as described inexample 1.

Fiber and liquid movement properties are as follows:

X-Factor 1.14 dimensionless Denier per fiber 169 dpf Channel width(avg.), 375 microns channel 1 (x₁, FIG. 14) Channel width (avg.), 58microns channel 2 (x₂, FIG. 14) Channel width (avg.), 837 micronschannel 3 (x₃, FIG. 14) Specific volume @ 0.05 3.19 cc/gm gram/deniertension Single fiber fiber area 14,181 microns² Single fiber total87,066 microns² channel area Single fiber capillary 8,795 microns²channel area for flow Single fiber percent 25 percent channels <300micron width Single fiber bulk factor 6.14 dimensionless Single fibertotal perimeter 2334 microns Single fiber specific 0.67 cc/gm capillaryvolume Single fiber specific 688 cm²/gm capillary surface area Specificliq. movement force 0.0430 dyne/den Single fiber initial 26.1 mm/secliquid velocity 8-fiber bundle initial 73.2 mm/sec liquid velocity8-fiber bundle maximum 0.1424 cc/(den*hr) potential flux Single fibermaximum 0.00981 cc/(den*hr) potential flux MPF_(B)/MPF_(SF) 14.5dimensionless single fiber vertical 1.71 cm rise after 15 min Bundlevertical rise 7.45 cm after 15 min VR_(B)/VR_(SF) 4.36 dimensionless

EXAMPLE 8

(Tee, PET, Egan)

This example describes the production of an undrawn continuous fiberyarn useful in bundle structures for enhanced transport of liquids. Theyarn is composed of 10 individual fibers, each having a T-shapedcross-section consisting of two arms of generally equal length formingthe bar or top of the T and a third longer arm forming the long or bodymember of the T. The two arms forming the top of the T are of generallythe same length. The two included angles between the body of the T andthe arms forming the top of the T are approximately equal and aregenerally somewhat greater than 90°, resulting in a large included anglebetween the arms forming the top of the T. This results in the formationof two channels having relatively large widths and areas and a thirdchannel having a relatively large channel width but considerably lessarea.

Poly(ethylene terephthalate), (PET), polymer having an IV of 0.77 andcontaining 0.2 percent Titanium dioxide (Tio₂) was used in preparingthis yarn. The polymer was dried to the same moisture level using thesame equipment as in example 1. The polymer was extruded at 280° C.using the same extruder as in example 1. The polymer was spun through aspinnerette, numbered I-1205, containing 10 individual orifices. Thedetails of each orifice and the general layout of the spinnerette holesare shown in FIGS. 15A-15D.

The fiber, which had an IV of 0.75, was spun in the same spinningcabinet as in example 1. The cross flow quench velocity was about 16.8meters/min. Spinning lubricant LK-5598-E10, the same as in example 1,was applied to the fiber at a level of 0.73 percent using the sameequipment as in example 1. The individual fibers averaged 160 dpf. Theyarn was taken up on a Leesona winder at 500 meters per minute.

A typical fiber cross-section is shown in FIG. 16. Fiber cross-sectionproperties and liquid movement properties for single fibers and 8-fiberfiber bundles were measured using the same methods as described inexample 1.

Fiber and liquid movement properties are as follows:

X-Factor 1.07 dimensionless Denier per fiber 160 dpf Channel width(avg.), 473 microns channel 1 (x₁, FIG. 16) Channel width (avg.), 572microns channel 2 (x₂, FIG. 16). Specific volume @ 0.05 5.93 cc/gmgram/denier tension Single fiber fiber area 13,478 microns² Single fibertotal 106,592 microns² channel area Single fiber capillary 13,365microns² channel area for flow Single fiber percent 0 percent channels<300 micron width Single fiber bulk factor 7.91 dimensionless Singlefiber total perimeter 2130 microns Single fiber specific 1.91 cc/gmcapillary volume Single fiber specific 416 cm²/gm capillary surface areaSpecific liq. movement force 0.0412 dyne/den Single fiber initial 36.5mm/sec liquid velocity 8-fiber bundle initial 71.3 mm/sec liquidvelocity 8-fiber bundle maximum 0.2950 cc/(den*hr) potential flux Singlefiber maximum 0.0219 cc/(den*hr) potential flux MPF_(B)/MPF_(SF) 13.4dimensionless Single fiber vertical 3.83 cm rise after 15 min Bundlevertical rise 5.19 cm after 15 min VR_(B)/VR_(SF) 1.36 dimensionless

FIG. 24 shows a generalized version of this fiber cross-section.

EXAMPLE 9

(C, PET, Egan)

This example describes the production of an undrawn continuous fiberyarn useful in bundle structures for enhanced transport of liquids. Theyarn is composed of 11 individual fibers, each having a C-shapedcross-section. This results in one major channel formed by the C shape.

Poly(ethylene terephthalate), (PET), polymer having an IV of 0.77 andcontaining 0.2 percent Titanium dioxide (TiO₂) was used in preparingthis yarn. The polymer was dried to the same moisture level using thesame equipment as in example 1. The polymer was extruded at 283° C.using the same extruder as in example 1. The polymer was spun through aspinnerette, numbered I-1200, containing 11 individual orifices. Thedetails of each orifice and the general layout of the spinnerette holesare shown in FIGS. 17A-17D.

The fiber, which had an IV of 0.75, was spun in the same spinningcabinet as in example 1. The cross flow quench velocity was about 16.7meters/min. Spinning lubricant LK-5598-E10, the same as in example 1,was applied to the fiber at a level of 0.61 percent using the sameequipment as in example 1. The individual fibers averaged 156 dpf. Theyarn was taken up on a Leesona winder at 500 meters per minute.

A typical fiber cross-section is shown in FIG. 18. Fiber cross-sectionproperties and liquid movement properties for single fibers and 8-fiberfiber bundles were measured using the same methods as described inexample 1.

Fiber and liquid movement properties are as follows:

X-Factor 1.20 dimensionless Denier per fiber 156 dpf Channel width(avg.), channel 1 (x₁, 686 microns FIG. 18) Specific volume @ 0.05gram/denier 3.56 cc/gm tension Single fiber fiber area 13,133 microns²Single fiber total channel area 111,081 microns² Single fiber capillarychannel area for 5,608 microns² flow Single fiber percent channels <3000 percent micron width Single fiber bulk factor 8.46 dimensionlessSingle fiber total perimeter 2055 microns Single fiber specificcapillary volume 0.74 cc/gm Single fiber specific capillary surface 458cm²/gm area Specific liq. movement force 0.0408 dyne/den Single fiberinitial liquid velocity 22.9 mm/sec 8-fiber bundle initial liquidvelocity 72.8 mm/sec 8-fiber bundle maximum potential flux 0.1632cc/(den*hr) Single fiber maximum potential flux 0.0593 cc/(den*hr)MPF_(B)/MPF_(SF) 27.6 dimensionless Single fiber vertical rise after 15min 1.49 cm Bundle vertical rise after 15 min 5.96 cm VR_(B)/BR_(SF)4.00 dimensionless

EXAMPLE 10

This example pertains to the fibers described in FIGS. 19A-19C. Thesefibers/bundles can be made on equipment described in example 1 and undersimilar spinning conditions. Bundles of these fibers behave similarly tothose shown in the other examples.

Cross sections of the type shown in FIG. 19A can be difficult to makebecause the melt surface tension tends to straighten out unbalancedintersections.

For example, to make the shallow channel polymeric structure with thesection shown in FIG. 19B, the steep channel spinnerette aperture shownin FIG. 19C is required.

The specific shape required depends on the polymer being extruded, theextrusion conditions, and the quenching conditions. Thus trial and erroris required to specify the exact spinnerette hole shape required.

This is true also for the fibers with the shapes shown in FIGS. 22A-22Bwhich require a spinnerette having the aperture shown in FIG. 22C.

EXAMPLE 11

This example discloses fibers of the type shown in FIG. 21A. Thesefibers,bundles can be made on equipment described in example 1 and undersimilar spinning conditions. Bundles of these fibers behave similarly tothose shown in the other examples.

There is surprising difficulty in producing these types of fiberswithout having a pronounced curl in the sides of the “H” as shown inFIG. 21C, because of the surface tension of the molten polymer.

These fibers have a reduced specific volume as compared to fibers withstraight vertical arms. This curvature is caused by the massiveshortening of the “bar” of the “H” because of surface tension. This“shortening” pulls at the center of the vertical walls during quenchingand thereby produces the “C” shaped vertical bar. This condition iscorrected by designing a spinnerette having the apertures shown in FIGS.21D-21G.

Obviously, the amount of the correction (i.e., bend in the arms of thespinnerette) required depends on the specific design being used and thesize and spinning conditions of the desired fiber. Therefore, some trialand error is required.

Bundles of these fibers behave similarly to those in the other examples.

Comparative Example 12

(H, PET, Egan)

This example describes the production of an undrawn continuous fiberyarn useful in bundle structures for enhanced transport of liquids. Theyarn is composed of 16 individual fibers, each having an “H”-shapedcross-section consisting of four arms of generally equal length and acrossbar connecting the arms to form the H. The four arms join thecrossbar to form two major channels that are generally rectangular inshape and that are approximately equal in area and channel width. Eachof the channels contains two included angles that are approximately 90°each.

Poly(ethylene terephthalate), (PET), polymer having an IV of 0.89 andcontaining 0.2 percent Titanium dioxide (TiO₂) was used in preparingthis yarn. The polymer was dried to the same moisture level using thesame equipment as in example 1. The polymer was extruded at 296° C.using the same extruder as in example 1. The polymer was spun through aspinnerette, numbered I-1011, containing 16 individual orifices. Thedetails of each orifice and the general layout of the spinnerette holesare shown in FIGS. 30A-30B.

The fiber, which had an IV of 0.68, was spun in the same spinningcabinet as in example 1. The cross flow quench velocity was about 33.6meters/min. Spinning lubricant LK-5598-E10, the same as in example 1,was applied to the fiber at a level of 0.82 percent using the sameequipment as in example 1. The individual fibers averaged 44.8 dpf. Theyarn was taken up on a Leesona winder at 500 meters per minute.

A typical fiber cross-section is shown in FIG. 31. Fiber cross-sectionproperties and liquid movement properties for single fibers and 8-fiberfiber bundles were measured using the same methods as described inexample 1.

Fiber and liquid movement properties are as follows:

X-Factor 1.78 dimensionless Denier per fiber 44.8 dpf Channel width(avg.), channel 1 (x₁, 37 microns FIG. 31) Specific volume @ 0.05gram/denier 2.35 cc/g tension Single fiber fiber area 3,767 microns²Single fiber total channel area 5,845 microns² Single fiber capillarychannel area for 5,405 microns² flow Single fiber percent channels <300100 percent micron width Single fiber bulk factor 1.55 dimensionlessSingle fiber total perimeter 744 microns Single fiber specific capillaryvolume 1.11 cc/gm Single fiber specific capillary surface 747 cm²/gmarea Single fiber slenderness ratio 19.8 diinensionless Specific liq.movement force 0.0515 dyne/den Single fiber initial liquid velocity 31.9mm/sec 8-fiber bundle initial liquid velocity 50.0 min/sec 8-fiberbundle maxiuium potential flux 0.0637 cc/(den*hr) Single fiber maximumpotential flux 0.0277 cc/(den*hr) MPF_(B)/MPF_(SF) 2.30 dimensionlessSingle fiber vertical rise after 15 min. 5.46 cm Bundle vertical riseafter 15 min. 12.4 cm VR_(B)/BR_(SF) 2.27 dimensionless

Notice that bundles of this fiber do not meet our limitation ofexceeding 0.14 (cc/den*hr) in the 8-fiber MPF_(B) test even though theindividual fibers are excellent wetters.

Comparative Example 13

(H, PET, Egan)

This example describes the production of an undrawn continuous fiberyarn useful in bundle structures for enhanced transport of liquids. Theyarn is composed of 32 individual fibers, each having an H-shapedcross-section consisting of four arms of generally equal length and acrossbar connecting the arms to form the H. The four arms join thecrossbar to form two major channels that are generally rectangular inshape and that are approximately equal in area and channel width. Eachof the channels contains two included angles that are approximately 90°each.

Poly(ethylene terephthalate), (PET), polymer having an IV of 0.76 andcontaining 0.2 percent Titanium dioxide (TiO₂) was used in preparingthis yarn. The polymer was dried to the same moisture level using thesame equipment as in example 1. The polymer was extruded at 283° C.using the same extruder as in example 1. The polymer was spun through anoval spinnerette, numbered I-1148, containing 32 individual orifices.The details of each orifice and the general layout of the spinneretteholes are shown in FIG. 32C.

The fiber, which had an IV of 0.63, was spun in the same spinningcabinet as in example 1. The cross flow quench velocity was about 42.7meters/min. Spinning lubricant LK-5598-E10, the same as in example 1,was applied to the fiber at a level of 1.02 percent using the sameequipment as in example 1. The individual fibers averaged 31.6 dpf. Theyarn was taken up on a Leesona winder at 1000 meters per minute.

A typical fiber cross-section is shown in FIG. 33. Fiber cross-sectionproperties and liquid movement properties for single fibers and 8-fiberfiber bundles were measured using the same methods as described inexample 1.

Fiber and liquid movement properties are as follows:

X-Factor 1.39 dimensionless Denier per fiber 31.6 dpf Channel width(avg.), channel 1 (x₁, 124 microns FIG. 33) Specific volume @ 0.05gram/denier 4.39 cc/gm tension Single fiber fiber area 2,659 microns²Single fiber total channel area 11,119 microns² Single fiber capillarychannel area for 12,153 microns² flow Single fiber percent channels <300100 percent micron width Single fiber bulk factor 4.18 dimensionlessSingle fiber total perimeter 737 microns Single fiber specific capillaryvolume 2.84 cc/gm Single fiber specific capillary surface 1244 cm²/gmarea Single fiber slenderness ratio 27.1 dimensionless Specific liq.movement force 0.0723 dyne/den Single fiber initial liquid velocity 23.2mm/sec 8-fiber bundle initial liquid velocity 53.2 mm/sec 8-fiber bundlemaximum potential flux 0.1546 cc/(den*hr) Single fiber maximum potentialflux 0.0643 cc/(den*hr) MPF_(B)/MPF_(SF) 2.41 dimensionless Single fibervertical rise after 15 min. 3.49 cm Bundle vertical rise after 15 min.9.32 cm VR_(B)/BR_(SF) 2.67 dimensionless

Notice that bundles of this excellently wetting single fiber onlyslightly exceed the limitation of MPF_(B) exceeding 0.14 (cc/den*hr).This is very surprising!

Comparative Example 14

(H, PET, Egan)

The spinnerette used was I-1148 with 32 holes (See FIG. 32) and thespinning system was the same as example 1. The polymer was semi dull PETwith an IV of 0.778. The spinning speed was 1500 meters/min. with aquench air flow of approximately 43 meters/min. at a melt temperature ofabout 285° C. The hydrophilic finish, LK 5598-E10, was applied atapproximately a 1.1% level.

Fiber, bundle and liquid movement properties are shown below:

X-Factor 1.76 dimensionless Denier per fiber 40 dpf Channel width (x₁,FIG. 34) 122 microns Specific volume @ 0.05 gram/denier 4.96 cc/gmtension Single fiber fiber area 3,363 microns² Single fiber totalchannel area 18,172 microns² Single fiber capillary channel area for18,172 microns² flow Single fiber percent channels <300 100 percentmicron width Single fiber bulk factor 5.40 dimensionless Single fibertotal perimeter 941 microns Single fiber specific capillary volume 3.17cc/gm Single fiber specific capillary surface 1017 cm²/gm area Singlefiber slenderness ratio 30.6 dimensionless Specific liq. movement force0.0729 dyne/den Single fiber initial liquid velocity 31.3 mm/sec 8-fiberbundle initial liquid velocity 57.6 mm/sec 8-fiber bundle maximumpotential flux 0.19 cc/(den*hr) Single fiber maximum potential flux 0.10cc/(den*hr) MPF_(B)/MPF_(SF) 1.90 dimensionless Single fiber verticalrise after 15 min. 3.7 cm Bundle vertical rise after 15 min. 9.7 cmVR_(B)/BR_(SF) 2.6 dimensionless

This particular sample represents about the best single fiber wetting“H” made to date. Yet, and very surprisingly, the bundle performanceexceeds 0.14 (cc/den*hr) by only 35% and the MPF_(B)/MPF_(SF) ratio isonly 1.90. This compares to Example 6 which exceeds the 0.14 (cc/den*hr)limitation by 157% and has a MPF_(B)/MPF_(SF) ratio of 14.7. Clearly,better performing bundles can be made from poorer performing singlefibers.

Based upon the figures of the cross-sections of the examples and themagnifications of those figures, the lengths and widths of the arms ofthe cross-sections were measured.

The arms of the cross-section of the fibers of example 1 have lengthsbetween about 280 and 360 microns and a length to width ratio (L/W)ranging between 22 and 27 for the width of the arms about half way alongthe arms.

For example 3, arm lengths are between about 120 and 380 microns and L/Wis between about 10 and 28.

For example 4, the arm lengths are between about 100 and 400 microns andL/W is between about 5 and 31.

For example 5, the arm lengths are between about 60 and 460 microns andthe L/W is between about 6 and 35.

For example 6, the arm lengths are between about 200 and 250 microns andL/W is between about 22 and 25.

For example 7, the arm lengths are between about 40 and 700 microns andL/W is between about 3 and 35.

For-example 9, the length of the “C” shaped cross-section is betweenabout 800 and 900 microns and L/W for the cross-section is between about40 and 60.

For examples 1-8, the widths of the arms at their midpoints are lessthan 20 microns and greater than 5 microns.

For example 9, the width of the cross-section at the center of the “C”shape is less than 40 microns.

The fibers of examples 3 and 7 have two relatively short arms and tworelatively long arms. The two relatively long arms of the fiber ofexample 7 form an angle of about 120°. The arms of the fiber of example3 form angles of about 90°. The fiber of example 5 has one relativelyshort arm and two relatively long arms. For example 5, the tworelatively long-arms form an angle of about 180° and each relativelylong arm forms an angle of about 90° with the relatively short arm.

The properties of examples 1-14 are summarized in Table Nos. IA-ID.

TABLE IA Specific Single Fiber Single Fiber Single Fiber Example Denierper Average Channel Volume Cross-Section Total Channels' Capillary Areafor No. x Fiber (dpf) Width (Microns) (cc/gm) Area (Microns)² Area(Micron)² Flow (Micron)² 1 1.21 123 (1) 332 5.58 10,311 80,770 10,492(2) 537 2 1.52 96 365 2.70  8,046 24,352  9,140 3 1.26 38 333 4.2811,570 77,083 22,156 4 1.22 123 (1) 358 4.83 10,313 63,911 14,890 (2)125 (3) 347 (4) 624 5 1.23 90.3 387 4.20 11,028 45,316 10,195 6 1.09 77390 7.22  6,464 63,657  9,490 7 1.14 169 (1) 375 3.19 14,181 87,066 8,795 (2)  58 (3) 837 8 1.07 160 (1) 473 5.93 13,478 106,592  13,365(2) 572 9 1.20 156 686 3.56 13,133 111,081   5,608 10  — — — — — — — 11 — — — — — — — 12  1.78 44.8  37 2.35  3,767  5,845  5,405 13  1.39 31.6124 4.39  2,659 11,119 12,153 14  1.76 40 122 4.96  3,363 18,172 18,172

TABLE IB Single Fiber's % of Channels Having Single Fiber Example aWidth <300 Single Fiber Total Perimeter Single Fiber Single Fiber SingleFiber No. (Microns) Bulk Factor (Microns) SCV (cc/gm) SCSA (cm²/gm)Slenderness Ratio(s) 1 0 7.83 1811 3.21 577 25.3 2 0 3.03 1379 0.60 87885.7 3 0 6.66 1953 2.77 1121  19.0 4 25  6.20 1897 2.21 726 18.8 5 05.11 2086 2.15 1269  49.1 6 0 5.11 1519 1.64 980 — 7 25  6.14 2334 0.67688 — 8 0 7.91 2130 1.91 416 — 9 0 8.46 2055 0.74 458 — 10  — — — — — —11  — — — — — — 12  100  1.55  744 1.11 747 19.8 13  100  4.18  737 2.841244  27.1 14  100  5.40  941 3.17 1017  30.6

TABLE IC Eight Fiber Single Fiber Specific Liquid Single Fiber FiberBundle Bundle Maximum Maximum Example Movement Initial Velocity InitialVelocity Potential Potential No. Force (dyne/den) (mm/s) (mm/s) Flux(MPF_(B))* Flux (MPF_(SF)) 1 0.0458 34.1 70.0 0.2701 0.0210 2 0.044722.3 54.0 0.0839 0.0154 3 0.0441 42.7 68.9 0.1942 0.0607 4 0.0480 38.273.0 0.2378 0.0334 5 0.0716 23.9 56.5 0.1407 0.0194 6 0.0613 27.6 69.70.3603 0.0246 7 0.0430 26.1 73.2 0.1424 0.00981 8 0.0412 36.5 71.30.2950 0.0219 9 0.0408 22.9 72.8 0.1632 0.0593 10  — — — — — 11  — — — —— 12  0.0515 31.9 50.0 0.0637 0.0277 13  0.0723 23.2 53.2 0.1546 0.064314  0.0729 31.3 57.6 0.19 0.10 *All bundle MPF value for an 8 (eight)fiber bundle.

TABLE ID Single Fiber Eight Fiber Bundle Ratio of Vertical ExampleVertical Rise After Vertical Rise After Rise_(B) to Vertical No. 15Minutes (cm) 15 Minutes (cm) MPF_(B)/MPF_(SF) Rise_(SF) (VR₈/VR_(SF)) 13.65 6.04 12.80 1.66 2 2.58 12.90 5.46 4.98 3 5.85 7.88 3.20 1.35 4 4.518.91 7.12 1.98 5 0.83 9.74 7.25 11.70 6 2.85 6.64 14.70 2.33 7 1.71 7.4514.50 4.36 8 3.83 5.19 13.40 1.36 9 1.49 5.96 27.60 4.00 10  — — — — 11 — — — — 12  5.46 12.40 2.30 2.27 13  3.49 9.32 2.41 2.67 14  3.70 9.702.30 2.60

Examples: Liquid Acquisition/Distribution Structures

EXAMPLES 15-22

In each of examples 15-22, approximately 25 milliliters (ml) of atextile tint was poured on the center of the structure at about 3ml/sec. A ½-inch thick layer of cellulose fluff pulp was placed underthe flow resistance layer to receive the insult. As shown in Table II,the “best” liquid distributors of the fibers tested in the sense ofdistributing the liquid uniformly over the length of the fluff wereclearly the bundles containing spontaneously wettable fibers. Bundles offibers of the invention described herein will perform at least as wellalso.

Table II also shows the actual measurements of the maximum “pumpingability” of the respective bundles as characterized by MPF_(B) in(cc/den*hr). The specific volume was measured by the method disclosed inU.S. Pat. No. 4,245,001, which is the same as the method disclosed inU.S. Pat. No. 4,829,761. The MPF_(B) increased dramatically from 0.002(cc/den*hr) for the round cross section fibers to 0.171 (cc/den*hr) forthe spontaneously wettable fibers.

The cross-sections of the fibers of the bundle used in examples 21 and22 are shown in FIGS. 46A-B. In examples 15-22, a perforatedpolyethylene film sold under the brand name Dri-Weave® was used as thetop layer and the flow resistance layer. It should be noted that bundlesof the fibers of examples 1-9 forming the distribution layer in theabsorbent article discussed for example 15-22 will function todistribute the liquid reasonably uniformly along the length of theabsorbent article.

The properties of examples 15-22 are summarized in Table II.

TABLE II Properties of Examples 15-22 Maximum Specific Potential ExampleCross* Vo Vo₈ Volume Flux* Liquid Distribution No. Section dpf mm/secmm/sec cc/gm cc/den*hr. in Pulp Underlay 15 Round 19.2 0 22.1 0.88 0.002Almost all the liquid moved into the center ⅓ of the pulp underlay 16Round 30.1 0 20.6 0.88 0.003 Almost all the liquid moved into the center⅓ of the pulp underlay 17 FIG. 45B 20.0 3.6 33.5 1.17 0.011 Some of theliquid was distributed to the outer ⅓rds of the pulp underlay. 18 FIG.45B 29.9 5.0 39.1 1.18 0.013 Some of the liquid was distributed to theouter ⅓rds of the pulp underlay. 19 FIG. 45D 12.7 0 37.1 1.82 0.031 Asignificant amount of liquid was moved to the outer ⅓rds of the pulpunderlay. 20 FIG. 45C 43.9 31.9 44.8 3.11 0.084 The liquid wasdistributed reasonably uniformly along the length of the pad. 21 FIG.46A 40.0 26.6 50.0 5.03 0.171 The liquid was distributed reasonablyuniformly along the length of the pad. 22 FIG. 46B 6.0 13.8 22.8 1.610.016 Some of the liquid was distributed to the outer ⅓rds of the pulpunderlay. *Examples 15-18 had ^(˜)0.5% LK 5598 - E10 as a surfacefinish. Example 19 had ^(˜)0.5% LK 1549 E25 as a surface finish, whichis   wt. % solids polyethylene glycol (400) monolaurate,   wt. % solidspolyethylene glycol (600) monolaurate, and   wt. % solids 4-cetyl,4-ethyl morpholinium ethosulfate. Example 20 had ^(˜)1.0% LK 5570 E10 asa surface finish, which is 49 wt. % solids polyethylene glycol (400)monolaurate, 49 wt. % solids polyethylene glycol (600) monolaurate, and2 wt. % solids 4-cetyl, 4-ethyl morpholinium ethosulfate. **MaximumPotential Flux (MPF_(B)) (cc/(den*hr)) = Vo₈ * 8 * 10⁻⁴ SV * (1 −0.7576/SV)

EXAMPLE 23

Example 23 was a repeat of the test conducted in examples 15-22 exceptthat the top sheet and the flow resistance layer were a standardcalendar bonded polypropylene nonwoven. Essentially the same resultswere achieved using the standard calendar bonded polypropylene nonwovenas the top sheet and the flow resistance layer as when the perforatedpolyethylene film was used.

EXAMPLE 24

Example 24 was also a repeat of examples 15-22 except that a top sheetavailable from Mölnlycke (i.e., another polymer film) was used for thetop sheet and flow resistance layer. Again, similar results wereobtained as in examples 15-22.

EXAMPLE 25

Example 25 was a repeat of example 19 except that the flow resistancelayer was the polymer film used in example 24. The liquidacquisition/distribution system of example 25 increased the distributionof the liquid toward the outer one third radius of the structure.

EXAMPLE 26

Example 26 is a comparison of performance of hydrophilic surfaces tonon-hydrophilic surfaces. The acquisition/distribution of a clean (i.e.,uncoated) Dri-Weave® top sheet and clean Dri-Weave® flow resistancelayer were compared to the acquisition,distribution structure in whichthe Dri-Weaves were coated with a very low level of the hydrophilicsurface lubricant Pegasperse 200, available from Lonza Inc. of Fairlawn,N.J. The structure with the Pegasperse 200 was clearly superior in itsdistribution capability than the structure having the clean surfaces.

EXAMPLE 27

Example 27 involved a structure having Dri-Weave® as the top layer andthe flow resistance layer, and the distribution layer was a thermalbonded (85% fiber/15% binder powder) 4DG nonwoven fabric. 4DG is thecross-section of the fibers of the bundle of example 22 and are shown inFIG. 46B. The 95.7 gms/meter² nonwoven was aligned with the machinedirection of the nonwoven being parallel to the major axis of thestructure. This system distributed the liquid but was not as effectiveas the structure used in example 19-22.

EXAMPLE 28

The liquid acquisition/distribution structure used in example 28 isshown in FIGS. 47A-B. Notice the 4 cm wide section in the flowresistance layer which is impermeable to flow. This system used thebundle material used in example 21 (shown in FIG. 46A) as thedistribution layer and gave excellent distribution of the liquid to theouter one third radius of the structure.

EXAMPLE 29

An absorbent product containing the liquid acquisition/distributionstructure used in example 28 is schematically shown in FIGS. 51A-B.Notice the liquid is intended to insult the surface over the smallaperture 574. The diameter of the small aperture 574 is 0.5 centimeters.The diameter of the larger apertures 573, 575 are 2.0 centimeters. Uponan insult to the top layer 571 above the aperture 574, the liquiddistribution layer 572 substantially uniformly distributes the liquidthrough the apertures 573, 574, 575 in order to more uniformlycommunicate the liquid to the absorbent core. The top layer wasDri-Weave®. The distribution layer 572 consisted of a 30,000 denierbundle of the fibers of example 6. The resistance layer 577 was apolyethylene film having the aperture 573, 574, and 575. The structureallowed the liquid to contact the absorbent core 578 at three distinctpoints to increase the utilization of the absorbent core's material.Obviously, the number of openings, their size, shape (e.g., round,rectangular, crescent, semicircular), and location can be selected toprovide the desired distribution of liquid to the core. Each openingshould connect the distribution layer to the absorbent core, and shouldbe in communication with the insult region via the distribution layer.

The distribution layer 572 may be a bundle of any of the fibers ofexamples 1-9. Preferably, the distribution layer 572 comprises a bundleof the fibers of example 6.

Fiber Measurement System

FIG. 27 shows a fiber wetting measurement system 300 useful fordetermining a liquid's velocity along the fiber or the bundle of fibers.The system 300 includes an image video display 301 for displaying highquality images of liquid-air-solid interfaces moving along the surfacesof the fiber or the bundle of fibers, a computer analysis systemgenerally indicated as 302 including a computer comprising input/outputdevices, a central processing unit, and memory, all of which arefunctionally interrelated as is well known in the art. The system 300also includes a liquid reservoir 305 in which there is one end of a tube307 for transporting the liquid from the liquid reservoir 305, a liquidpump 306 for pumping a metered amount of the liquid from the liquidreservoir 305 through the tube 307 to a fiber retaining mechanism 308.The fiber retaining mechanism 308 positions the fiber or the bundle offibers retained thereby between the video camera 304 and a means forproviding uniform bright field illumination 109. The means for providingthe uniform bright field illumination 309 may be a combination of alight homogenizer and a fluorescent ring shaped light source wherein thelight homogenizer is between the fiber retaining mechanism 308 and thering shaped light. source.

FIG. 28 is a top-sectional view of a liquid dispensing tip 310 forproviding a metered amount of liquid to a fiber through the tube 307shown in FIG. 27. The radii 311-315 are about 0.029 inches, 0.125inches, 0.063 inches, 0.096 inches, and 0.076 inches, respectively. Themetering pump (not shown) provides consistent liquid delivery on demand.

FIG. 29 is a side-sectional view of dispenser tip 310. The lengths 316and 317 are about 0.35 and about 0.60 inches, respectively.

The system 300 provides for collection of image data showing themovement of the liquid-air-solid interface along the fiber or the bundleof fibers retained by the retaining mechanism 308. The system 300provides a means to determine Vo, and therefore a means to determineMPF. The computer analysis system 302 is programmed to identify theliquid-air-solid interface position along the fiber in each frame ofimage data and to calculate the Initial Velocity, Vo, of theliquid-air-solid interface using that data. Details of the computerprogram are set forth in the Microfiche Appendix.

The liquid supply to the fiber or the bundle of fibers is controlled bya metering system which includes the liquid pump 306 to provide thedesired quantity (a metered amount) of the liquid to a local reservoir310 a of liquid adjacent the fiber or the bundle of fibers. The meteringsystem includes the dispensing tip 310 shown in FIGS. 28 and 29, forreceiving the metered amount of the liquid. The arrow at the bottom ofFIG. 29 indicates the direction of flow of the metered amount of theliquid from the tube 307 to the local reservoir 310 a in the dispensingtip 310.

FIG. 52 is a photocopy of a photograph of the fiber retaining mechanism308 showing the tip 310, the fiber retaining clamps 580, 581, and afiber 582 retained by the clamps 580, 581. The fiber retaining mechanism308 retains the fiber 582 adjacent and directly above the center of thelocal reservoir 310 a. (The arrow on the photocopy of the photographpoints in the up direction.) The metered amount of the liquid issufficient to over fill the local reservoir 310 a so that the liquidprotrudes above the upper surface of the local reservoir 310 a andthereby contacts and surrounds the portion of the fiber 582 directlyabove the local reservoir 310 a.

FIG. 53 is a photocopy of a photograph of an image frame 590 generatedon the image video 301 by the video camera 304. The image frame 590shows the fiber 582, the liquid dispensing tip 310, the horizontal lines583, 584, and the vertical marker line 585. The horizontal lines 583,584 delimit a visual region of interest or ROI. As shown in FIG. 53, thefiber 582 is suspended so that a portion 586 is directly above the topof the liquid dispensing tip 310. (The arrow on the image frame 590shows the up direction.)

FIG. 54 is a schematic of the type of histogram generated from the imagedata for the purpose of setting a threshold for determining when tobegin image data collection in the system shown in FIG. 27. Thehorizontal axis in FIG. 54 identifies a digital value of intensityassociated with the light received by a pixel in the video camera 304.The vertical axis in FIG. 54 identifies the number of pixels having eachdigital value of intensity. Because of the bright field illumination dueto the illuminating means 309, all pixels in the ROI have an intensitytowards the upper end of the intensity scale. The histogram in FIG. 54includes data only for the pixels in the ROI between the lines 583, 584.

FIG. 54 also identifies a digital value indicated as the threshold. Thethreshold is a value that may be graphically determined by the operatorof the system shown in FIG. 27. The threshold is set to an intensityvalue that is below the lowest digital value for intensity of any pixelin the ROI and above the digital value for the intensity at a locationof the fiber or the bundle of fibers when the fiber or the bundle offibers is wetted by the liquid in the reservoir.

FIG. 55 consists of four images of the ROI 591-594 at different times.Images 591-594 are sequential in time, showing the movement of theliquid-air-solid interface from where the liquid contacts the fiber orthe bundle of fibers along the fiber or the bundle of fibers. The ROI591 shows the liquid air interface 591 a. The ROI 592 shows theliquid-air-solid interface 592 a. The ROI 593 shows the liquid-air-solidinterface 593 a. In the ROI 594, the liquid-air-solid interface isbeyond the right end edge of FIG. 55. The convex meniscus 595 formingthe liquid-air interface above the liquid dispensing tip 310 is shown inthe ROI 594.

FIG. 56 shows a video image including a graph 600, formula used forcalculating values 601, data from a series of tests 602, and calculatedvalues 603 based upon the experimental results shown in the graph 600.The graph 600 is a graph of position versus time for the location of theliquid-air-solid interface along the length of the fiber 582.

Use of the Fiber Measurement System

The Vo determination includes the following general procedure. Atensioned (≈0.1 g/d) fiber or bundle is mounted to the fiber retainingmechanism 308 in a predetermined location within the field of view ofthe video camera 304. A fixed metered volume of test liquid (i.e.Syltint® Red or Red Test Solution) is brought into contact with thebundle. The fixed volume of liquid used for a single fiber measurement(as opposed to a bundle measurement) is 0.00677 milliliters³. (Thisvolume of liquid was provided in the system 300 by setting the meteringpump liquid volume setting to 115.) Data from thirty digital videoframes per second are recorded in the computer 302's memory for a periodof four seconds. The slope of the line defined by the square of thedistance traveled by the liquid front versus time is determined. A leastsquares fit or similar procedure may used to determine a value for theslope, or the slope may be estimated from a plot of the data. From thisslope, the initial liquid velocity Vo is calculated using the formula:

Vo(mm/sec)=[Slope(mm²/sec)/(4*0.022 sec)]^(½).

The capillary channel area for flow and the denier per filament (dpf)are determined. The capillary channel area for flow is determined asdescribed herein. It is well known in the art how to determine thedenier of the fiber.

From Vo, dpf, and capillary channel area for flow, the (two-way)MPF_(SF) in cubic centimeters per gram per hour is calculated as:

Two-way MPF_(SF)(cc/gm*hr)=2*0.1620*Vo(mm/sec)*(capillary channel areafor flow (microns²))*(1/dpf)

The arbitrary length of the fiber used in the above formula is 20centimeters. Thus, the weight in grams of the fiber is the weight of a20 cm long piece of the fiber.

The “two-way” calculation accounts for the fact that the liquid movesalong the fiber in both directions even though Vo is determined only onone side of the drop contact, which is why the two-way MPF definitionincludes a factor of two. These measurements and calculations areconducted on a sufficient number of filaments to develop statisticallysound data. Typically for a given type of fiber (i.e., a fiber producedfrom a spinnerette aperture under a set of conditions), twenty pieces ofthe fiber are cut and three measurements of the initial liquid velocityare made on each of the piece of the fiber, for a total of sixtymeasurements. The average of the 60 measurements (or wets) is used todetermine Vo.

The 20 cm length used to calculate MPF_(SF) is quite arbitrary althoughit is the approximate length of a feminine napkin. After seriousconsideration the inventors believe that a more standard unit system forMPF is cubic centimeter per denier per hour cc/(den*hr) instead ofcc/(gm*hr). The units of conversion from cc/(gm*hr) to cc/(den*hr)changes the length in the equation for MPF from 20 cm to 9,000 meters,because 9,000 meters is the standard length for the denier unit. All ofthe MPF values reported herein are in cc/(den*hr) unless otherwisestated. The conversion of MPF (cc/gm*hr.) to MPF (cc/den*hr.) isaccomplished by the following equation:

MPF(cc/gm hr)*(20 cm/900,000 cm)=MPF(cc/gm*hr)*(1/45,000)=MPF(cc/den*hr)

Thus dividing by 45,000 converts to MPF from cc/(gm*hour) tocc/(den*hr).

During the procedures for determining the values for MPF of a fiber orof a bundle of fibers care is taken to avoid stretching the fibers, toavoid crimps in the fiber, to avoid separation of wetting liquid in thepumping system, to maintain room temperature (21.1° C.) and normalhumidity (65% Relative Humidity) thereby avoiding condensation, tomaintain sufficient optical contrast to be able to observe the positionof the liquid on the fiber, to avoid movement of the fiber during themeasurements, and to avoid contamination of the fibers.

From time to time it is necessary to calibrate the metering pump toensure that a given scale setting on the pump corresponds to a knowndelivered volume of liquid. This can be accomplished by setting a seriesof several pump scale settings (say 100, 200, 300, 400), manuallypulsing the pump a large number of times at each of these settings (say400, 200, 150, 100 times, respectively), and diverting the Syltintdischarge of the pump into a calibrated 10 ml glass cylinder. The volumeof liquid collected at each setting is divided by the number of pulses(strokes) used at that setting to calibrate the metering pump setting tothe volume of liquid delivered at that setting.

The video scale of the system 300 should also be calibrated to ensurethat the lengths automatically determined in the computer based upon theimage data correspond to physical lengths. The video scale should becalibrated when a change has been made in the video camera or in thelighting system, such as a change in the video camera's position orfocus. The video calibration may be accomplished by placing a ruler inthe location of the fiber sample holder so that a ten centimeter sectionis in the field of view and adjusting the external light source so thatthe ruler divisions are clearly visible. The ten centimeter length ofthe ruler can be defined in the image data and the computer's variablesidentifying the scale may be adjusted so that the computer'scalculations define the centimeter section of the ruler as tencentimeters.

Determination of the Initial Velocity of liquid along the bundle is verysimilar to the determination of the Initial Velocity of liquid along thesingle fiber. The primary difference is that measurements are made upona bundle of fibers grouped together rather than a single fiber. The testis performed using the same system 300 used for single fibers.Differences between measurements of single fibers and bundles of fibersare described below.

Sample preparation for use in the system 300 of a bundle of fibersincludes separating single fibers from a ninety centimeter long fullyarn strand and then combining the individual fibers into an 8 fiberbundle of essentially parallel fibers.

The weights for tensioning are clipped to each end of the ninetycentimeter long bundle to produce a bundle tension of about 0.1gm/denier on the bundle (based on the total denier of the bundle). Thebundle is placed in and on top of the fiber mounting grooves of themounting system in a manner to keep the fibers grouped as close togetherand as parallel as practical. Measurements are made on three separatelocations on each ninety centimeter long bundle. Measurements areobtained from approximately 20 bundles for a total of sixty wets.

A volume of liquid of 0.013984 ml for a bundle of eight 50 dpf fibersand a volume of liquid of 0.033198 ml for a bundle of eight 150 dpffibers was metered. The volume of liquid that is metered may bedetermined in accordance with the metering of liquid described formeasuring individual fibers. Generally, the amount of liquid metered permeasurement is a constant plus a volume linearly proportional to the dpfof the fibers of the bundle. However, the exact amount of liquid meteredper measurement is not critical.

The use of the system 300 for determining the maximum potential flux(MPF) and the Initial Velocity (Vo) is described hereinbelow in thediscussion of FIGS. 57-60. One embodiment of a computer program fordetermining MPF is set forth in the Microfiche Appendix.

FIG. 57 is a flowchart showing an overview of the algorithm forcalculating MPF and Vo using the system 300 shown in FIG. 27. Thatalgorithm includes the sub-algorithm 700 for setting up the system 300for data collection, the sub-algorithm 701 for acquiring data, thesub-algorithm 702 for analyzing data, and the end of the routine 703.

FIG. 58 shows the sub-algorithm 700 for setting up for data collectionwhich includes the scale determining algorithm 704 and the thresholdsetting algorithm 705.

The scale determining algorithm 704 includes the step 705 of placing aruler in the field of view at the same distance from the video camera304 as the fiber 582. In step 706, two points defining an interval alongthe image of the ruler appearing in the image video 301 are marked withgraphical markers controlled by a graphical interface, such as a mouse.In step 707, the actual interval between the two points is read from theindicia on the image of the ruler and input into the computer via thekeyboard. The computer runs an algorithm to determine the number ofpixels spanning the interval defined by the two points. In step 708, thecomputer calculates the number of pixels per length by dividing thedetermined number of pixels spanning the interval by the length of theinterval, thereby determining the scale of the image of the fiber or thebundle of fibers 582.

The purpose of the algorithm 705 for setting the threshold is to enablethe computer to automatically recognize and locate the liquid-air-solidinterface, and to thereby measure the advancement of the liquid alongthe length of the fiber or the bundle of fibers. In step 709, the userdefines the region of interest, ROI, which is the region in the videoimage containing the image of the fiber. The ROI in FIG. 53 is limitedto the region between the two lines 583, 584. In step 710, the computeris instructed to plot a histogram of the number versus the digitizedpixel intensity for the pixels in the region of interest and display theplot on the image video 301.

Since the system 300 includes the bright field background provided bythe means 309, all of the pixels have an intensity towards the upper endof the scale. This is why the histogram shown in FIG. 54 has intensityonly towards the upper end of the digitized intensity scale. Theshoulder in the histogram appearing in FIG. 54 towards lower intensityrepresents the decrease in intensity for the pixels imaging the fiber582 shown in FIG. 53 relative to the bright background. The decreasedintensity is because the fiber blocks or scatters some of the light.Based upon the data in the histogram, an intensity below the intensityof the pixels that are present in the ROI is defined as the threshold.The intensity of the threshold is set below the intensity of any pixelin the ROI and above the intensity of the image of the fiber when thefiber is wetted by the liquid.

Setting the threshold is step 711. In step 712, the marker location forthe threshold is set. FIG. 53 shows the marker location 585 for thethreshold. The marker location for the threshold is set laterallydisplaced from the region of the fiber immediately above the liquiddispensing tip 310 so that the threshold (1) will not be triggered bythe formation of the convex meniscus of the liquid protruding up fromthe reservoir of the liquid dispensing tip 310 but (2) will be triggeredwhen the liquid begins propagating along the fiber or the bundle offibers thereby crossing the marker location 585.

The threshold and the marker location for the threshold are used tobegin data collection and to extrapolate when the liquid contacts thefiber. Data collection begins when the intensity of the pixel (oraverage intensity of the pixels, if a group of pixels is used) at themarker location falls below the threshold value. The intensity of thepixel or pixels at the marker location falls below the threshold valuewhen the liquid covers the fiber or the bundle of fibers at the markerlocation. Since the marker location is immediately adjacent to theliquid dispensing tip 310, and since the fiber or bundle of fibers arespontaneously transporting, the liquid covers the fiber at the markerlocation very shortly after the liquid contacts the fibers. Byextrapolation from the data of liquid-air-solid interface versus time,it appears that the liquid covers the marker location along the fiber inno more than a few milliseconds. Since the system 300 records a newimage frame every thirtieth of a second, the time at which the intensityat the marker location falls below the threshold is a good approximationto the time when the liquid contacts the fiber.

FIG. 55 shows a display on the image video 301 reconstructing fourimages 591-594 of the ROI at four consecutive times. Image 591 shows theliquid-air-solid interface 591 a at a position along the fiber or bundleof fibers 582 that is relatively close to the top of the liquiddispensing tip 310 as compared to the liquid-air-solid interfacepositions 592 a and 593 a in the images 592 and 593 that occursequentially at subsequent times. Image 594 shows the fiber or bundle offibers 582 in ROI entirely coated with the liquid. The metered amount ofliquid is sufficient to fill the local reservoir of the liquiddispensing tip 310 such that the liquid projects up from the from therim of the reservoir of the tip and forms a meniscus 595 having apositive curvature such that the liquid extends around the fiber or thebundle of fibers.

FIG. 59 shows the algorithm for acquiring data using the system 300.Data acquisition is initiated after the system has been set up for datacollection using the algorithm shown in FIG. 58. However, it should benoted that the recalibration of the scale and the resetting of thethreshold each time the system is used are advisable, but not essential.

In step 720, the system is instructed to begin the data acquisition. Instep 721, the system compares the intensity at the threshold markerlocation with the threshold. If the intensity is not below thethreshold, the system executes step 722 to determine if a timeout hasoccurred. If a timeout has occurred, the system ends the dataacquisition in step 723. If a timeout has not occurred, pursuant to step722, the system repeats the comparison in step 721.

If, in step 721, the system 300 determines that the intensity at themarker location is below the threshold intensity, the system 300 sets arunning variable n=0 in step 724.

Next, in step 725, the system acquires data for the image frame n at thetime T_(n). Next, in step 726, the system examines the data in the ROIto determine the location, X_(n), of the liquid-air-solid interface forimage frame n. The system records the location of the liquid-air-solidinterface and the time of the image frame n (X_(n), T_(n)).

Next, in step 727, the system 300 increments the value of n by 1. Next,in step 728, the system determines whether n is greater 120. If n is notgreater than 120, the system returns to step 725 and acquires the nextimage frame. The system is set so that the time between image frames is1/30th of a second (0.033 seconds). Therefore, when n=120, the systemhas been acquiring data for approximately four seconds.

If, in step 728, n is greater than 120, the system does not return tostep 729 to acquire more data.

When n exceeds 120, the data acquisition for the wetting of the fiber orthe bundle of fibers ends. At this point, the operator can start thedata acquisition routine again after moving the fiber or the bundle offibers to a location so that the dispensing tip 310 is not adjacent awet region of the fiber or the bundle of fibers. Alternatively, theoperator can instruct the system to begin the analysis of the data forsome set, j, of acquired data (X_(i), T_(i))_(j). (The subscript irefers to different data during a single wetting. The subscript j refersto data for different wettings.) In any case, when several data sets forseveral distinct wettings of the fiber or bundle of fibers have beenrecorded, the algorithm for calculating the Initial Velocity Vo and theMaximum Potential Flux MPF is executed. That algorithm is shown in FIG.60.

In step 729, the system performs a curve fit for the 120 pairs of valuesfor the position of the liquid-air-solid interface at the times T to theequation X² equals a constant, K, times the time, T. (X_(i) ²=K_(j)*T_(i) for i=1 to 120 and for a specified integral value of j.)Step 729 is performed for each of the data sets, j, that has beenacquired for a particular fiber or bundle of fibers. That is, positionversus time of the liquid-air-solid interface is acquired at multiplelocations along a single fiber or bundle of fibers, or is acquired alongdifferent segments of the same type of fiber. Each set of data points(X, T) is fit to the foregoing formula in order to determine a value ofK_(j) for the jth wetting of the fiber or the bundle of fibers.

Next, in step 730, an average value of K is determined. The averagevalue of K is the average of all K_(j) values obtained in step 729 forthe same type of fiber or the bundle of fibers. In this context, thesame type means fibers or bundles of fibers formed using the sameprocess as one another and thereby nominally having the samecross-sectional shape and surface composition.

Next, in step 731, the parameter Vo (Initial Velocity) is calculated asVo=one half of the quantity of the square root of K in squarecentimeters per second (cm²/sec) divided 0.022 seconds. The quantity Vois termed the Initial Velocity because it approximates the velocity thatthe liquid would have at 0.022 seconds after the liquid first contactsthe fiber or the bundles of fibers. That approximation is based upon aphysical model balancing forces between the driving force and thevelocity-proportionally viscous force. That is, the model (which resultsin the equation of motion X²=KT) is an approximation assuming a solutionto the equation of motion for the liquid that ignores inertial terms.Note that actual gravitational forces do not exist along the length ofthe fiber or the bundle of fibers because the fiber or the bundle offibers are held horizontal during the measurements. The value for timeof 0.022 seconds after the time of which the optical intensity fallsbelow threshold at the marker location in step 721 is in the definitionof Vo because that time is long enough after the actual time at whichthe liquid contacts the fiber that differences between the model'svelocity Vo and the actual velocity at t=0.022 seconds areinsignificant. In this context, insignificant means that the differenceis less than about ten percent.

Finally, in steps 732, the MPF, which is a function of Vo andpredetermined quantities, is calculated.

Red Test Solution: Composition and Preparation

In preparing a sample of Red Test Solution, components (a) through (g)comprising

(a) 80.3 grams (0.414 moles) dimethyl isophthalate,

(b) 26.9 grams (0.091 moles) dimethyl-5-sodiosulfoisophthalate,

(c) 54.1 grams (0.51 moles) diethylene glycol.

(d) 37.4 grams (0.26 moles) 1,4-cyclohexanedimethanol,

(e) 0.75 grams (0.0091 moles) anhydrous sodium acetate,

(f) 100 ppm Titanium catalyst as titanium tetraisopropoxide, and

(g) 15.0 grams (0.037 moles) of red colorant

are added to a 50 mL round bottom flask. The flask is fitted with astirrer, condensate take off and nitrogen inlet head. The flask andcontents are immersed into a Belmont metal bath and heated for two hoursat 200-220° C. while ester interchange occurs. To carry out thepolycondensation reaction, the temperature is increased to about 250° C.and the flask is held under vacuum ≦0.5 mm Hg for about 20 minutes. Adark red polymer is produced which is granulated by grinding in a Wileymill.

The dark red polymer is a water dispersible polymer containing 10percent by weight of the red colorant. The dark red polymer has an IV of0.235, a T_(g) at 57.51° C., a weight average molecular weight of12,728, a number average molecular weight of 5,035 by Gel PermeationChromotography and a polydispersity value of 2.53.

After granulation, slowly add 100 grams of the dark red polymer granulesto 250 mls of boiling millipore water. The water is then slowly cooledwith stirring until the dispersion is uniform so no solid residueremains. The resulting dispersion weighs 333 grams which is equivalentto 30 percent by weight of the dark red polymer in millipore water. Add10 mls of the 30 percent by weight dispersion to an equal portion ofmillipore water to make a 50/50 dispersion. Add 10 mls of the 50/50dispersion to 5 mls of distilled water to make the final test solutionwhich is a 90/10 water/red polymer dispersion.

The Red Test Solution while appearing to be very stable, should bestirred or mixed thoroughly once a month to insure a uniform test fluid.The Red Test Solution has a shear viscosity of 1.5 centipoise and asurface tension of 56 dynes/cm.

Note that any aqueous fluid with sufficient color contrast and viscosityless than 3 centipoise could have been used as the test fluid. However,the results for MPF depend strongly on the surface tension and theviscosity of the test fluid. Thus, if an aqueous fluid with highersurface tension and equal viscosity to the test fluids above is used,the MPF numbers will be larger for a given fiber test sample. If anaqueous fluid with a higher viscosity and equal surface tension to thetest fluids above is used, the MPF numbers will be smaller.

Obviously, numerous modifications and variations of the presentinvention are possible in light of the above teachings. It is thereforeto be understood that within the scope of the appended claims, theinvention may be practiced otherwise than as specifically describedherein.

What is claimed is:
 1. A bundle of synthetic fibers for transportingaqueous fluids, wherein said bundle comprises at least two fibers, atleast one of said two fibers having a non-round cross-section and saidbundle having (A) a Specific Volume greater than 4.0 cc/gm, (B) a[Vertical Rise of the Bundle (VR_(B))]/[Vertical Rise of the SingleFiber (VR_(SF))] greater than or equal to 1.3, and (C) a Vertical Riseof the Bundle (VR_(B)) greater than or equal to 4.0 centimeters.
 2. Thebundle of synthetic fibers of claim 1 having an average inter-fibercapillary width of from 25 to 400 microns.
 3. The bundle of syntheticfibers of claim 1 wherein the cross-section and the surface compositionof the fibers satisfy the inequality: (Pγ cos(θa))/d>0.03 dynes/den,wherein P is the perimeter of the cross-section of the fiber, γ is thesurface tension of the liquid, (θa) is the advancing contact angle ofthe liquid measured on a flat surface made from the same material as thefiber and having the same surface treatment and d is the denier of thefiber.
 4. The bundle of synthetic fibers of claim 1 wherein saidcross-section of said fiber defines a first arm having a length greaterthan 40 microns.
 5. The bundle of synthetic fibers of claim 4 whereinsaid first arm has a length greater than 100 microns.
 6. The bundle ofsynthetic fibers of claim 1 wherein said fibers have a Single Fiber BulkFactor of greater than 4.0.
 7. The bundle of synthetic fibers of claim 6wherein the Specific Volume is between 4.0 and 10.0.
 8. The bundle ofsynthetic fibers of claim 7 wherein the Specific Volume is between 4.0and 7.2.
 9. The bundle of synthetic fibers of claim 1 whereinVR_(B)/VR_(SF) is greater than 2.0.
 10. The bundle of synthetic fibersof claim 9 wherein VR_(B)/VR_(SF) is about 2.3.
 11. The bundle ofsynthetic fibers of claim 1 wherein VR_(B)/VR_(SF) is between 1.66 and11.7.
 12. The bundle of synthetic fibers of claim 1 wherein VR_(B) isbetween 4.0 and 15 centimeters.
 13. The bundle of synthetic fibers ofclaim 1 wherein the fibers have a denier between 15 and
 250. 14. Thebundle of synthetic fibers of claim 13 wherein the fibers have a denierbetween 30 and 170.